Judge Pechman of the U.S. District Court for the Western District of Washington issued an order on October 21, 2011 granting Plaintiffs' motion to certify a class of investors in certain Washington Mutual RMBS on a substantially narrower basis than Plaintiffs had requested. The lawsuit, which brings claims under Section 11 of the Securities Act of 1933, involves 6 offerings that collectively contained 123 separate tranches of certificates. Plaintiffs, who purchased in only 13 of the tranches, sought to certify a class of all investors in any tranche of any of the 6 offerings. The court found that each tranche represents a different security and that Plaintiffs lacked standing to sue as to any tranche in which they had not purchased. Judge Pechman thus both denied class certification and granted judgment on the pleadings in favor of Defendants as to those tranches. As to the remaining 13 tranches in which Plaintiffs had purchased, the court found that class certification was appropriate. Decision.