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ARM Indexes: Treasury Securities, 1975-1979


Full Name: Auction Average of (3 or 6) Month Treasury Bills;
Treasury Security Adjusted to a Constant Maturity of (1,3,5) Year(s)
Source: Federal Reserve
Compiled by: HSH Associates, Riverdale, NJ

The Treasury Security (or "T-Sec") indexes are calculated by the Treasury Department and reported by the Federal Reserve; these indexes have both weekly and monthly values. Most lenders use the weekly value on their ARMs. These indexes reflect the state of the economy, and respond quickly to economic changes.

The most commonly used is the One Year Treasury Security; it's used on ARMs with annual rate adjustments. Confusion can arise when some lenders use the term "One Year Treasury Bill." Most one-year ARMs are tied to the Constant Maturity of the One Year Treasury Security.

Your new interest rate will be determined by the T-Sec value 30 to 45 days before your next rate change. A margin (which averages 2.75 percent) is added to this index by the lender when your ARM's rate is adjusted.

To compute your new mortgage rate, take the correct index value and add your margin; then, round the result to the nearest one-eighth percent. (Some contracts call for rounding to the next highest one-eighth percent.) If, for example, the index value is 6.04 percent and your margin is 2.75 percent, the sum is 8.79%; rounding to the nearest one-eighth percent would set your ARM rate at 8.75%. Remember to check for any 'caps' on your ARM. Usually, they limit any rate changes to 2 percent over (or under) your old interest rate. Your mortgage disclosure specifies the exact index, whether the weekly or monthly value applies, the lead time for your index, the margin, and any caps.

See our ARM Check Kit for complete instructions and worksheets.

For the latest index values, see the Current Indexes Table.

Please Note: The Treasury Constant Maturity series are BIG files. Some browsers (and machines with limited memory) may not be able display these files in their entirety. If you don't see the entire history, save the file and view it off-line.


Week   3 Month T-Bill    6 Month T-Bill    1 Year T-Sec      3 Year T-Sec      5 Year T-Sec
Ending   Weekly   Monthly  Weekly   Monthly  Weekly   Monthly  Weekly   Monthly  Weekly   Monthly

03-Jan-75    7.113    6.493    7.101    6.525     7.29     6.83     7.33     7.23     7.35     7.41
10-Jan-75    6.698             6.682              7.01              7.24              7.33
17-Jan-75    6.678             6.646              7.02              7.29              7.45
24-Jan-75    6.369             6.373              6.70              7.26              7.48
31-Jan-75    5.606             5.825              6.44              7.08              7.39
07-Feb-75    5.669    5.583    5.736    5.674     5.93     5.98     6.76     6.65     7.15     7.11
14-Feb-75    5.800             5.800              6.07              6.75              7.17
21-Feb-75    5.408             5.483              5.86              6.46              6.99
28-Feb-75    5.455             5.675              6.08              6.62              7.13
07-Mar-75    5.637    5.545    5.742    5.635     6.06     6.11     6.65     6.81     7.19     7.30
14-Mar-75    5.622             5.655              6.00              6.67              7.21
21-Mar-75    5.376             5.473              6.09              6.87              7.36
28-Mar-75    5.542             5.669              6.24              7.02              7.45
04-Apr-75    5.562    5.694    5.786    6.012     6.65     6.90     7.46     7.76     7.73     7.99
11-Apr-75    6.021             6.351              6.97              7.74              7.98
18-Apr-75    5.538             5.843              6.83              7.70              7.95
25-Apr-75    5.653             6.067              7.02              7.90              8.10
02-May-75    5.716    5.315    6.158    5.649     6.89     6.39     7.86     7.39     8.08     7.72
09-May-75    5.356             5.724              6.61              7.59              7.82
16-May-75    5.182             5.481              6.30              7.31              7.68
23-May-75    5.115             5.412              6.21              7.22              7.61
30-May-75    5.206             5.469              6.26              7.27              7.64
06-Jun-75    5.258    5.192    5.505    5.463     6.20     6.29     7.18     7.17     7.56     7.51
13-Jun-75    5.080             5.283              5.89              6.91              7.28
20-Jun-75    4.767             5.129              6.20              7.07              7.40
27-Jun-75    5.665             5.935              6.74              7.46              7.75
04-Jul-75    6.009    6.164    6.262    6.492     6.92     7.11     7.58     7.72     7.87     7.92
11-Jul-75    6.203             6.510              6.96              7.59              7.88
18-Jul-75    6.045             6.344              6.97              7.65              7.86
25-Jul-75    6.247             6.626              7.30              7.81              7.97
01-Aug-75    6.318    6.463    6.719    6.940     7.38     7.70     7.94     8.16     8.05     8.33
08-Aug-75    6.456             6.864              7.63              8.11              8.31
15-Aug-75    6.349             6.809              7.73              8.19              8.35
22-Aug-75    6.452             7.000              7.80              8.27              8.40
29-Aug-75    6.593             7.085              7.71              8.09              8.28
05-Sep-75    6.381    6.383    6.866    6.870     7.62     7.75     8.09     8.29     8.24     8.37
12-Sep-75    6.389             6.889              7.70              8.32              8.42
19-Sep-75    6.444             6.901              7.88              8.44              8.48
26-Sep-75    6.316             6.824              7.75              8.23              8.28
03-Oct-75    6.547    6.081    6.980    6.385     7.70     6.95     8.27     7.81     8.34     7.97
10-Oct-75    6.239             6.571              7.25              8.03              8.14
17-Oct-75    6.045             6.243              7.00              7.92              8.01
24-Oct-75    5.887             6.156              6.73              7.65              7.84
31-Oct-75    5.685             5.974              6.44              7.41              7.72
07-Nov-75    5.602    5.468    5.792    5.751     6.30     6.49     7.30     7.46     7.67     7.80
14-Nov-75    5.279             5.483              6.38              7.32              7.67
21-Nov-75    5.471             5.796              6.58              7.59              7.92
28-Nov-75    5.520             5.933              6.68              7.59              7.91
05-Dec-75    5.550    5.504    5.995    5.933     6.75     6.60     7.55     7.43     7.87     7.76
12-Dec-75    5.633             6.144              6.88              7.65              7.96
19-Dec-75    5.491             5.914              6.65              7.44              7.75
26-Dec-75    5.340             5.678              6.32              7.25              7.58

02-Jan-76    5.208    4.961    5.507    5.238     6.18     5.81     7.12     6.99     7.50     7.46
09-Jan-76    5.226             5.521              5.96              7.02              7.44
16-Jan-76    4.826             5.066              5.77              6.94              7.42
23-Jan-76    4.783             5.046              5.74              7.00              7.48
30-Jan-76    4.763             5.052              5.68              6.98              7.47
06-Feb-76    4.811    4.852    5.066    5.144     5.82     5.91     7.00     7.06     7.47     7.45
13-Feb-76    4.872             5.133              5.82              7.11              7.49
20-Feb-76    4.854             5.171              5.96              7.10              7.44
27-Feb-76    4.870             5.204              6.02              7.05              7.40
05-Mar-76    5.258    5.047    5.724    5.488     6.39     6.21     7.30     7.13     7.57     7.49
12-Mar-76    5.060             5.487              6.23              7.16              7.54
19-Mar-76    4.981             5.459              6.23              7.13              7.51
26-Mar-76    4.890             5.283              6.06              7.00              7.40
02-Apr-76    4.929    4.878    5.327    5.201     6.12     5.92     7.05     6.84     7.40     7.25
09-Apr-76    4.957             5.293              5.96              6.88              7.28
16-Apr-76    4.830             5.068              5.75              6.70              7.16
23-Apr-76    4.763             5.089              5.84              6.74              7.19
30-Apr-76    4.909             5.230              6.02              6.91              7.30
07-May-76    4.921    5.185    5.339    5.600     6.09     6.40     7.00     7.27     7.37     7.59
14-May-76    5.072             5.426              6.29              7.18              7.54
21-May-76    5.250             5.726              6.54              7.38              7.68
28-May-76    5.495             5.908              6.69              7.52              7.77
04-Jun-76    5.578    5.443    5.952    5.784     6.69     6.52     7.45     7.31     7.72     7.61
11-Jun-76    5.459             5.768              6.52              7.33              7.63
18-Jun-76    5.380             5.695              6.48              7.28              7.58
25-Jun-76    5.356             5.722              6.45              7.24              7.53
02-Jul-76    5.368    5.278    5.754    5.597     6.46     6.20     7.27     7.12     7.58     7.49
09-Jul-76    5.412             5.768              6.28              7.17              7.52
16-Jul-76    5.190             5.430              6.12              7.03              7.42
23-Jul-76    5.226             5.536              6.21              7.16              7.51
30-Jul-76    5.194             5.497              6.11              7.06              7.47
06-Aug-76    5.151    5.153    5.473    5.416     6.10     6.00     6.96     6.86     7.45     7.31
13-Aug-76    5.181             5.422              6.02              6.86              7.34
20-Aug-76    5.143             5.390              6.00              6.83              7.26
27-Aug-76    5.138             5.380              5.93              6.81              7.22
03-Sep-76    5.091    5.075    5.351    5.311     5.91     5.84     6.75     6.66     7.17     7.13
10-Sep-76    5.087             5.333              5.89              6.71              7.17
17-Sep-76    5.099             5.309              5.87              6.66              7.14
24-Sep-76    5.028             5.236              5.76              6.61              7.10
01-Oct-76    5.072    4.930    5.325    5.073     5.80     5.50     6.59     6.24     7.06     6.75
08-Oct-76    5.087             5.265              5.63              6.33              6.87
15-Oct-76    4.905             5.024              5.38              6.02              6.62
22-Oct-76    4.799             4.911              5.41              6.15              6.65
29-Oct-76    4.929             5.093              5.50              6.35              6.81
05-Nov-76    4.862    4.810    5.030    4.944     5.45     5.29     6.31     6.09     6.74     6.52
12-Nov-76    4.892             5.044              5.51              6.33              6.79
19-Nov-76    4.890             5.018              5.33              6.11              6.58
26-Nov-76    4.596             4.682              5.05              5.79              6.20
03-Dec-76    4.466    4.355    4.567    4.513     4.92     4.89     5.65     5.68     6.02     6.10
10-Dec-76    4.383             4.516              4.93              5.67              6.09
17-Dec-76    4.360             4.508              4.91              5.69              6.14
24-Dec-76    4.269             4.500              4.86              5.67              6.11
31-Dec-76    4.296             4.474              4.87              5.71              6.14

07-Jan-77    4.407    4.597    4.555    4.783     5.02     5.29     5.83     6.22     6.24     6.58
14-Jan-77    4.613             4.803              5.22              6.20              6.59
21-Jan-77    4.668             4.868              5.38              6.33              6.65
28-Jan-77    4.700             4.905              5.50              6.48              6.80
04-Feb-77    4.720    4.662    5.008    4.896     5.57     5.47     6.54     6.44     6.88     6.83
11-Feb-77    4.625             4.840              5.40              6.39              6.75
18-Feb-77    4.633             4.862              5.37              6.35              6.73
25-Feb-77    4.668             4.872              5.54              6.51              6.95
04-Mar-77    4.708    4.613    4.943    4.883     5.55     5.50     6.49     6.47     6.96     6.93
11-Mar-77    4.652             4.965              5.52              6.50              6.96
18-Mar-77    4.545             4.813              5.49              6.46              6.90
25-Mar-77    4.553             4.826              5.49              6.44              6.89
01-Apr-77    4.609    4.540    4.870    4.790     5.45     5.44     6.45     6.31     6.94     6.79
08-Apr-77    4.585             4.846              5.43              6.45              6.94
15-Apr-77    4.561             4.767              5.39              6.22              6.73
22-Apr-77    4.494             4.708              5.41              6.23              6.70
29-Apr-77    4.518             4.617              5.54              6.36              6.80
06-May-77    4.807    4.942    5.052    5.193     5.67     5.84     6.49     6.55     6.93     6.94
13-May-77    4.822             5.131              5.87              6.58              6.98
20-May-77    4.996             5.234              5.93              6.57              6.95
27-May-77    5.143             5.353              5.91              6.56              6.91
03-Jun-77    4.993    5.004    5.192    5.198     5.86     5.80     6.49     6.39     6.87     6.76
10-Jun-77    5.048             5.234              5.83              6.46              6.84
17-Jun-77    5.000             5.167              5.80              6.35              6.72
24-Jun-77    5.012             5.222              5.79              6.35              6.72
01-Jul-77    4.965    5.146    5.173    5.351     5.72     5.94     6.32     6.51     6.68     6.84
08-Jul-77    5.044             5.246              5.81              6.40              6.78
15-Jul-77    5.163             5.356              5.88              6.47              6.80
22-Jul-77    5.214             5.436              5.99              6.55              6.86
29-Jul-77    5.163             5.364              6.08              6.61              6.94
05-Aug-77    5.424    5.500    5.691    5.810     6.24     6.37     6.74     6.79     7.03     7.03
12-Aug-77    5.353             5.679              6.34              6.81              7.06
19-Aug-77    5.669             5.978              6.48              6.85              7.08
26-Aug-77    5.553             5.891              6.42              6.78              7.00
02-Sep-77    5.574    5.770    5.849    5.991     6.35     6.53     6.72     6.84     6.93     7.04
09-Sep-77    5.554             5.845              6.41              6.75              6.98
16-Sep-77    5.887             6.098              6.57              6.84              7.05
23-Sep-77    5.851             5.976              6.55              6.86              7.06

30-Sep-77    5.982             6.185              6.63              6.94              7.10
07-Oct-77    6.108    6.188    6.286    6.410     6.79     6.97     6.97     7.19     7.18     7.32
14-Oct-77    6.156             6.381              7.05              7.18              7.32
21-Oct-77    6.282             6.496              7.07              7.28              7.36
28-Oct-77    6.207             6.478              6.96              7.28              7.39
04-Nov-77    6.278    6.160    6.508    6.433     7.05     6.95     7.32     7.22     7.45     7.34
11-Nov-77    6.187             6.464              6.99              7.24              7.36
18-Nov-77    6.092             6.373              6.92              7.17              7.27
25-Nov-77    6.084             6.385              6.91              7.19              7.30
02-Dec-77    6.057    6.063    6.371    6.377     6.91     6.96     7.22     7.30     7.35     7.48
09-Dec-77    6.049             6.347              6.94              7.27              7.44
16-Dec-77    6.073             6.371              6.94              7.27              7.46
23-Dec-77    5.985             6.338              6.97              7.33              7.51
30-Dec-77    6.152             6.460              7.01              7.39              7.57

06-Jan-78    6.144    6.448    6.423    6.685     7.03     7.28     7.40     7.61     7.59     7.77
13-Jan-78    6.682             6.848              7.43              7.71              7.85
20-Jan-78    6.535             6.759              7.34              7.66              7.81
27-Jan-78    6.429             6.709              7.30              7.65              7.79
03-Feb-78    6.440    6.457    6.715    6.740     7.28     7.34     7.58     7.67     7.74     7.83
10-Feb-78    6.476             6.743              7.31              7.62              7.79
17-Feb-78    6.452             6.745              7.38              7.71              7.87
24-Feb-78    6.460             6.755              7.38              7.74              7.90
03-Mar-78    6.429    6.319    6.709    6.644     7.34     7.31     7.71     7.70     7.87     7.86
10-Mar-78    6.349             6.676              7.29              7.69              7.85
17-Mar-78    6.302             6.624              7.28              7.64              7.81
24-Mar-78    6.207             6.547              7.25              7.65              7.81
31-Mar-78    6.310             6.666              7.39              7.79              7.94
07-Apr-78    6.417    6.306    6.717    6.700     7.43     7.45     7.82     7.85     7.97     7.98
14-Apr-78    6.373             6.743              7.40              7.81              7.95
21-Apr-78    6.140             6.563              7.42              7.83              7.96
28-Apr-78    6.294             6.777              7.57              7.95              8.05
05-May-78    6.460    6.430    6.935    7.019     7.68     7.82     7.99     8.07     8.09     8.18
12-May-78    6.464             6.986              7.78              8.06              8.17
19-May-78    6.318             7.014              7.86              8.07              8.17
26-May-78    6.476             7.141              7.93              8.15              8.24
02-Jun-78    6.658    6.707    7.160    7.200     7.92     8.09     8.19     8.30     8.27     8.36
09-Jun-78    6.626             7.095              7.89              8.16              8.25
16-Jun-78    6.618             7.121              8.03              8.19              8.29
23-Jun-78    6.666             7.228              8.22              8.40              8.43
30-Jun-78    6.967             7.396              8.32              8.51              8.49
07-Jul-78    7.058    7.074    7.447    7.471     8.34     8.39     8.51     8.54     8.50     8.54
14-Jul-78    7.188             7.515              8.42              8.56              8.56
21-Jul-78    7.113             7.497              8.42              8.55              8.56
28-Jul-78    6.935             7.425              8.39              8.55              8.53
04-Aug-78    6.895    7.036    7.362    7.363     8.23     8.31     8.36     8.33     8.36     8.33
11-Aug-78    6.808             7.172              8.13              8.21              8.25
18-Aug-78    6.887             7.259              8.38              8.37              8.37
25-Aug-78    7.267             7.471              8.40              8.35              8.35
01-Sep-78    7.323    7.836    7.550    7.948     8.47     8.64     8.37     8.41     8.39     8.43
08-Sep-78    7.659             7.742              8.46              8.35              8.37
15-Sep-78    7.695             7.793              8.56              8.34              8.35
22-Sep-78    7.884             7.979              8.72              8.45              8.46
29-Sep-78    8.106             8.276              8.81              8.49              8.52
06-Oct-78    8.161    8.132    8.377    8.493     8.88     9.14     8.50     8.62     8.52     8.61
13-Oct-78    8.256             8.422              8.93              8.47              8.49
20-Oct-78    8.209             8.561              9.17              8.57              8.59
27-Oct-78    7.900             8.612              9.24              8.69              8.66
03-Nov-78    8.454    8.787    8.982    9.204     9.95    10.01     9.12     9.04     8.89     8.84
10-Nov-78    9.028             9.419             10.16              9.10              8.86
17-Nov-78    8.593             9.291              9.89              8.95              8.78
24-Nov-78    8.696             8.996              9.92              8.96              8.81
01-Dec-78    9.166    9.122    9.330    9.397    10.11    10.30     9.16     9.33     8.92     9.08
08-Dec-78    8.984             9.220             10.14              9.12              8.89
15-Dec-78    8.929             9.263             10.12              9.19              8.97
22-Dec-78    9.237             9.524             10.49              9.52              9.25
29-Dec-78    9.336             9.580             10.54              9.59              9.32

05-Jan-79    9.388    9.351    9.550    9.501    10.51    10.41     9.58     9.50     9.30     9.20
12-Jan-79    9.316             9.443             10.51              9.60              9.30
19-Jan-79    9.411             9.534             10.50              9.59              9.26
26-Jan-79    9.289             9.475             10.31              9.42              9.10
02-Feb-79    9.324    9.265    9.376    9.349    10.13    10.24     9.15     9.29     8.94     9.13
09-Feb-79    9.186             9.307             10.19              9.20              9.05
16-Feb-79    9.257             9.342             10.19              9.28              9.13
23-Feb-79    9.293             9.370             10.33              9.39              9.24
02-Mar-79    9.451    9.457    9.498    9.458    10.36    10.25     9.45     9.38     9.28     9.20
09-Mar-79    9.364             9.415             10.30              9.39              9.20
16-Mar-79    9.475             9.457             10.31              9.39              9.20
23-Mar-79    9.498             9.483             10.22              9.38              9.21
30-Mar-79    9.498             9.437             10.11              9.33              9.18
06-Apr-79    9.593    9.493    9.496    9.498    10.09    10.12     9.34     9.43     9.18     9.25
13-Apr-79    9.649             9.572             10.24              9.46              9.28
20-Apr-79    9.613             9.627             10.04              9.44              9.24
27-Apr-79    9.115             9.295             10.12              9.47              9.28
04-May-79    9.498    9.579    9.570    9.562    10.30    10.12     9.54     9.42     9.36     9.24
11-May-79    9.621             9.617             10.27              9.54              9.35
18-May-79    9.506             9.459             10.09              9.45              9.27
25-May-79    9.744             9.602              9.95              9.27              9.08
01-Jun-79    9.526    9.045    9.409    9.062     9.88     9.57     9.19     8.95     9.01     8.85
08-Jun-79    9.554             9.425              9.74              9.06              8.91
15-Jun-79    8.957             9.047              9.48              8.90              8.80
22-Jun-79    8.869             8.873              9.61              8.99              8.89
29-Jun-79    8.802             8.903              9.39              8.81              8.76
06-Jul-79    8.968    9.262    8.867    9.190     9.44     9.64     8.78     8.94     8.73     8.90
13-Jul-79    9.265             9.164              9.53              8.88              8.86
20-Jul-79    9.336             9.255              9.70              8.96              8.94
27-Jul-79    9.479             9.473              9.82              9.05              8.98
03-Aug-79    9.154    9.450    9.301    9.450     9.72     9.98     9.01     9.14     8.96     9.06
10-Aug-79    9.320             9.320              9.72              8.98              8.93
17-Aug-79    9.495             9.481              9.95              9.06              9.01
24-Aug-79    9.599             9.504             10.14              9.20              9.11
31-Aug-79    9.680             9.645             10.28              9.40              9.27
07-Sep-79    9.855   10.182    9.775   10.125    10.75    10.84     9.68     9.69     9.42     9.41
14-Sep-79   10.531            10.294             10.91              9.66              9.36
21-Sep-79   10.353            10.315             10.89              9.72              9.41
28-Sep-79    9.989            10.114             10.81              9.71              9.45
05-Oct-79   10.313   11.472   10.327   11.339    11.02    12.44     9.85    10.95     9.61    10.63
12-Oct-79   10.808            10.662             12.50             10.65             10.42
19-Oct-79   11.836            11.716             12.68             11.01             10.70
26-Oct-79   12.932            12.651             13.31             11.83             11.37
02-Nov-79   12.256   11.868   12.193   11.856    12.91    12.39    11.64    11.18    11.25    10.93
09-Nov-79   12.098            12.086             12.94             11.56             11.21
16-Nov-79   12.026            11.945             12.31             11.12             10.95
23-Nov-79   11.944            12.035             12.45             11.31             11.09
30-Nov-79   11.018            11.022             11.76             10.64             10.42
07-Dec-79   11.927   12.071   11.767   11.847    11.93    11.98    10.61    10.71    10.34    10.42
14-Dec-79   12.054            11.769             12.28             10.86             10.45
21-Dec-79   12.228            11.999             11.91             10.68             10.39
28-Dec-79   12.074            11.854             11.84             10.71             10.51
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