I used study note of Schweser, 2009 version. On page 225, book 4, it reads as follows:
“Now we’ll assume management enters a pay-fixed, receive-floating swap to change the nature of a floating rate liability. For simplicity, we’ll assume the swap floating payments are the same as the floating rate liability payments so that they exactly offset one another. The result is that management has effectively changed the liability form floating to fixed without changing the firm’s assets.
Since fixed-rate instruments have a longer duration than floating-rate instruments, the addition of the swap has increased the duration of the firm’s liabilities and narrowed the difference between the asset and liability durations. The bottom line is that the firm’s equity, with a shortened duration, is now less sensitive to changes in interest rates than before management entered the swap. If rates rise, the value of the equity will fall less than before management entered the swap. If rates rise, the value of the equity will fall less than before managment used the swap. To protect against risign rates, management has sacrificed some of the upside potential from falling rates.”