Sybase Inc. and Michaels Stores Inc. topped this year's list of the nation's poorest-performing companies drawn up by the $128-billion California Public Employees' Retirement System. CalPERS picked nine companies in need of improved stock prices as part of its quest to pressure lagging companies to improve their performance. Irving, Texas-based Michaels and Sybase of Emeryville were picked for "some of the most egregious corporate governance practices and poor performance among their industry peers," CalPERS said. CalPERS said 37% of shareholder capital was shed at Sybase, a database software company, between 1993 and 1996. Shareholder capital slipped 7% at Michaels, an arts and crafts retailer, during that time. Others on the list: Advanced Micro Devices Inc.; Electronic Data Systems Corp.; International Flavors & Fragrances Inc.; forest products company Louisiana Pacific Corp.; diesel engine maker Stewart & Stevenson Services; tire seller TBC Corp.; and plastics company A. Schulman.