Shares of AMC Entertainment Holdings (NYSE: AMC) are bouncing back from their Thursday sell-off, rising 3.4% through 9:40 a.m. EDT today. The reason: This morning, S&P Global Ratings upgraded the stock's credit from CCC+ to CCC-. To do this, says the agency, AMC must apply the cash it has gained from stock sales to pay down some of its debt, refinance the rest at lower interest rates, and benefit from higher revenue as moviegoers return to its theaters.