content_image/76067.jpg content_image/76070.jpg
## (3) Securities 

## Investment Securities 

The amortized cost and fair values of investment securities are as follows (in thousands): 

<img src='content_image/76067.jpg'>

The amortized cost and fair values of investment securities at December 31, 2001, by contractual maturity, are as shown in the following table (dollars in thousands): 

<img src='content_image/76070.jpg'>

1 Calculated ona taxable equivalent basis using a 39% effective tax rate. 

2 The average expected lives of mortgage-backed securities were 0.54 years based upon current prepayment assumptions. 

>The nominal yield on mortgage-backed securities is based upon prepayment assumptions at the purchase date. Actual yields earned may differ significantly based upon actual prepayments. 

‘Expected maturities may differ from contractual maturities because borrowers may have the right to call or prepay obligations with or without penalty. 

During 2000, BOK Financial sold a mortgage-backed security with a remaining amortized cost of $175 thousand. The acquisition cost of this security was $4.9 million. Therefore, these sales were permitted under the sales deemed to be.at maturity provisions of Statement of Financial Accounting Standards No. 115, “Accounting for Certain Investments in Debt and Equity Securities.” 

