dmrktrading

484
Original Floating rate (Pay Floating, Quarterly) = -0.5 * .25 = -0.125
Now by converting to fixed since you feared rising interest rates
your duration of the Swap = -0.75 * Maturity (Pay Fixed) + 0.125 (receive fixed)
so your net duration changed to -0.75 * Maturity of Loan.
IF loan was a 1 year loan, your net duration increased 6 fold = (0.75/0.125)
that is all :!