The stock market is up slightly as Chesapeake Energy (NYSE:CHK) jumped 8.41 percent and financial stocks rose broadly. However enthusiasm was tempered by a downgrade of American Express (NYSE:AXP).

The S&P 500 Index is up 4.64 points, or 0.37 percent, to trade at 1,248.55 at 3:39 p.m. EDT. The Dow Jones Industrial Average is up 6.47 points, or 0.06 percent, to trade at 11,498.38.  The Nasdaq Composite is up 0.44 percent.

Chesapeake Energy was boosted by news that activist investor Carl Icahn is increasing his stake in the company and is in talks with management about maximizing shareholder value.   

Financials are up broadly as Goldman Sachs (NYSE:GS) rose 1.54 percent, American International Group (NYSE:AIG) jumped 2.09 percent, and JPMorgan (NYSE:JPM) climbed 0.98 percent.

American Express (NYSE:AXP), however, plunged 3.89 percent after Stifel Nicolaus downgraded it from ‘buy’ to hold’ on the Federal Reserve’s rule on debit card interchange fees.