Provenz

Plaintiffs Diane Provenz and Ahikim Eiz-enberg, on behalf of themselves and all other similarly situated purchasers of stock of MIPS Computer Systems, Inc. (MIPS), appeal the district court’s grant of summary judgment in favor of all defendants. Plaintiffs brought this action against MIPS and MIPS’ officers and directors, Charles M. Boesenberg, Robert C. Miller, David G. Lud-vigson, Stephen R. Bennion, and William D. Jobe, under section 10(b) of the Securities Exchange Act of 1934, 15 U.S.C. § 78j(b), and Rule 10b-5 of the Securities Exchange Commission, 17 C.F.R. § 240 .10b-5. The plaintiffs also appeal the district court’s order awarding costs to defendants. The district, court had jurisdiction under 28 U.S.C. § 1331 . We have jurisdiction under 28 U.S.C. § 1291 . We affirm in part, reverse in part, and remand.

BACKGROUND

The plaintiffs brought this securities fraud case as a class action. The class period runs from January 31, 1991, through October 9, 1991. Plaintiffs allege that, during the class period, the value of MIPS’ stock was artificially inflated because defendants recognized revenue before the revenue was earned and failed to disclose to the market information about…