Shares of AMC Entertainment AMC.N and BlackBerry Ltd BB.N jumped 19.3% and 22.1%, extending a red-hot rally driven by small-time investors on online trading platforms. Concerns over a labor shortage fueling inflationary pressures have raised fears that the Federal Reserve would pare back its crisis support sooner than expected, despite central bank officials' reassurances to the contrary. The Fed on Wednesday said it would begin to unwind the corporate bond holdings it acquired last year to calm credit markets, adding that it was unrelated to its monetary policy.