Wall Street’s backlash against 3D movies is growing serious. Just weeks after movie executives and investors wondered how well 3D films would do this summer, they’ve begun to ask much tougher questions including: When will movie theater chains begin to cancel orders for 3D projection equipment? And could continued weakening in ticket sales force AMC Entertainment to shelve its plan to go public and raise as much as $450 million?

Defenders of the technology are urging everyone to wait and see whether there’s an uptick in 3D ticket sales for Paramount’s Transformers: Dark Of The Moon, which opens July 1, and Warner Bros’ Harry Potter And The Deathly Hallows, Part II, which opens July 15. The films should “help provide for a more positive outlook” for 3D in general and particularly for 3D technology company RealD, says Merriman Capital analyst Eric Wold.

But investors didn’t appear to agree on Friday. RealD’s stock price fell 13.2% to $20.90 the day after executives responded to the Street’s concerns with talking points that simply urged people not to read too much into disappointing 3D sales for just a few films. RealD shares now have lost 41.3% of their value since May 19. “While management dismisses a change in consumer enthusiasm toward 3D, the public is speaking and 3D is simply being overused with ticket premiums far too high,” says BTIG analyst Rich Greenfield — who has a “sell” rating on RealD.

Exhibitors also are losing patience. Regal Entertainment’s stock price is down 16.7% since mid-May. Cinemark is down 12.6% since this beginning of this month. “When 3D was first introduced the public got really excited,” says Imax CEO Rich Gelfond. “But over time it’s going to be on a movie-by-movie basis. In some cases it will work. And in others it won’t.”