By David Crane, includes "... Footnote 21 of Berkshire Hathaway's most recent annual report discloses the following about its pension plan assumptions ... In contrast, compare the approach taken by the California State Teachers Retirement System (CalSTRS), which posts this statement in its most recent annual report: "Investment return rate and discount rate is 7.5 percent."  You will notice that CalSTRS chooses to employ the same rate for both purposes..."