By Liz Moyer

Investing.com -- Stocks jumped on Wednesday after positive earnings from Nike helped calm investor fears about inflation and interest rates. Here are the midday movers for Dec. 21.

• AMC Entertainment Holdings Inc (NYSE: AMC) shares rose 3.5% after the largest theater chain operator said it was no longer in talks to buy theaters from Cineworld (LON:CINE), the owner of Regal cinemas in the U.S.

• Nike Inc (NYSE: NKE) shares rose 13.3% after the athletic apparel maker reported a better-than-expected quarter and raised its revenue forecast, saying demand remained strong. It was also continuing to work through inventory challenges.

• Rite Aid Corporation (NYSE: RAD) stock fell 15.3% after the pharmacy retail chain reported higher than expected revenue for the quarter but a drop from last year because of declining demand for COVID-19 vaccines and tests. Its quarterly loss of $1.23 a share was wider than last year's 67 cent a share loss.

• Six Flags Entertainment New (NYSE: SIX) stock was up 11.9% after the amusement park operator attracted an activist investor. Land&Buildings Investment Management has reportedly taken a 3% stake in the company and has suggested it sell or spin off real estate holdings.

• Carnival Corporation (NYSE: CCL) shares rose 4.4% after the cruise operator reported a narrower-than-expected quarterly loss despite missing revenue estimates. Higher costs for food and fuel ate into results but bookings volume gained momentum after loosening COVID restrictions.