57 L.Ed.2d 253 98 S.Ct. 2380 437 U.S. 340 OPPENHEIMER FUND, INC., et al., Petitioners,v.Irving SANDERS et al. No. 77-335. Argued Feb. 28-March 1, 1978. Decided June 19, 1978. Syllabus Respondents brought a class action under Fed.Rule Civ.Proc. 23(b)(3) on behalf of themselves and a class of purchasers against petitioners (including an open-end investment fund, […]