California State Sen. Tom Hayden and Assemblyman Wally Knox today introduced legislation requiring the $171 billion California Public Employees Retirement System and the $111 billion California State Teachers Retirement System to divest themselves of more than $900 million in tobacco stocks over an 18-month period. Similar measures have failed on previous efforts, but advocates hope last years -51.5% return on tobacco stocks will bolster arguments that investing in such stocks is imprudent. The bill, AB 107, strips out other CalPERS-related legislation. It will be considered first in the state Senate. As of Dec. 31, CalPERS had $589 million in tobacco stocks, while CalSTRS had $319 million.