After more modest-than-expected opening for Paramount’s 3D toon, the question facing DreamWorks Animation is whether “How to Train Your Dragon” will be able to hold onto screens long enough to build a blockbuster-caliber audience.While films like “Dragon” generally have a long life in theaters, particularly in advance of school holidays, the 3D phenom is challenging that assumption because of upcoming releases fighting for digital screens. Those fears seemed to have landed on Wall Street Monday where shares of DreamWorks Animation SKG Inc. dropped 9.2%. But exhibs don’t seem overly concerned. . According to Par, the 3D toon, which launched with $43.7 million, will retain all 2,178 3D locations as it goes head-to-head this weekend with Warner Bros.’ 3D actioner “Clash of the Titans.” But while it will maintain an even number of multiplexes, the toon could lose screens within the plexes to “Titans.” Imax is contracted to a six-week engagement of “Dragon” on 186 3D runs. Warners is expected to launch “Clash” at fewer than 2,000 3D locations, leaving the remaining screens for Disney’s holdover “Alice in Wonderland.” “Alice” played at a total 1,450 3D locations last weekend, about 640 fewer than the week before, with that figure expected to drop substantially on Friday. So what does this mean for “Clash”? Tracking for the film has been extremely positive, especially among males. Yet, with early negative reviews, the film could face an uphill battle among broader demos in repeat frames. As of January, the National Assn. of Theater Owners reported a total of 3,378 3D-equipped screens in the U.S., and recent funding from the Digital Cinema Implementation Partners (DCIP) has helped screen count rise to a current 4,100. “Dragon’s” 3D engagements repped 65% of the toon’s total weekend domestic gross at about 60% of total locations. Leading up to the toon’s release, some exhibs increased 3D ticket prices by as much as 8%, one factor that may have affected the toon’s modest earnings. But “Dragon” could follow the pattern of some non-franchise toons which have built a following more gradually. “Dragon’s” hold on its 3D count, positive reviews and strong word-of-mouth could still lead to a healthy run. Toon should also benefit from spring break and Easter. DWA stock fell $3.47 to close Monday at $39.34. The studio saw similar results in 2005 after “Madagascar” launched with a disappointing domestic take of $47 million, driving stock prices down 9%. But the toon played steadily for many weeks and went on to cume $556 million worldwide. Disney’s “Ratatouille,” which launched with $47 million in 2007, saw similar tracking as “Dragon,” with a little-known voice cast and no added support from a franchise. The pic went on to earn $629 million worldwide. DWA is set to release its latest 3D “Shrek Forever After” on May 21.