Exhibition company investors are growing anxious about the possibility that Hollywood studios will soon release new films to home video during the 90-day period when theaters insist on offering them exclusively.

Stock prices for all of the major chains are down this week, following Warner Bros.’ Kevin Tsujihara’s comment on Tuesday that earlier home releases have become “imperative.” Bloomberg added to concerns with a report yesterday that studios want to rent films on VOD  as early as two weeks after they hit theaters, charging from $25 to $50.

AMC Entertainment is off 7.9% this week, and 3.9% today. Regal’s down 9.2% for the week, and 2.0% today. Cinemark shares fell 9.7% this week, and 3.5% today. Imax is down 10% for the week, and was flat today. (Carmike is just down 2.9% this week as investors await Justice Department approval for its sale to AMC.)

Exhibition companies may suffer additional body blows next week when several studio owners address Wall Street at the annual UBS Global Media and Communications Conference.

Fox CEO James Murdoch — who in September attacked “these crazy hold-backs that theater owners put in place” — delivers a keynote on Monday. Attendees also will hear from Netflix Chief Content Officer Ted Sarandos, whose company is producing movies for simultaneous release online and in theaters. And Tsujihara’s boss, Time Warner CEO Jeff Bewkes, addresses the group on Tuesday.