Mark enters a short sale on February 20, 2002 for 100 shares. He covers his short position on February 20, 2004. The brokers commission is 0.5%. Mark must deposit a haircut equal to 40% of the proceeds received on the sale of the stock. The short rebate is 5% compounded quarterly. A dividend on this stock of $1.50 per share was payable on February 20, 2003 and on February 20, 2004 (assume the second dividend payment took place right before Mark covered the short). The bid price on February 20, 2002 is $30 per share with a bid-ask spread of $0.50. The bid price on February 20, 2004 is $28 per share with a bid-ask spread of $0.40. Find Marks effective rate of interest on his investment.