Happy Friday, shareholders! Stocks closed this week with the biggest weekly gain since November for the S&P 500, which closed at 756.55. The Dow Jones nudged up 0.8 percent to 7,223.98. Citigroup, Bank of America and JP Morgan Chase all posted stellar numbers this week after releasing positive first quarter reports. Elsewhere, Humana Inc., the second-biggest provider of health insurance in the U.S. rose 7.7 percent, and Merck rose 13 percent off speculation that they would soon be acquired.