LITTLE ROCK (AP) _ The board of the Arkansas Teacher Retirement System on Tuesday became the latest pension fund to dump Putnam Investments amid accusations of improper mutual fund trading.

Arkansas' pullout involves more than $500 million in investments.

Last week, pension funds in six other states _ Iowa, Massachusetts, New York, Pennsylvania, Rhode Island and Vermont _ closed their accounts with Putnam, taking more than $4 billion with them.

The state of Massachusetts and Securities and Exchange Commission have accused the Boston-based firm is accused of turning a blind eye to improper fund trading. In some cases, that improper trading is alleged to have been done by former fund managers at the expense of mutual fund shareholders. The firm denies any wrongdoing.

More defections could be ahead.

Also Tuesday, the California state treasurer recommended that the California Public Employees Retirement System and the California State Teachers Retirement Systems, the largest and third-largest pension funds in the country, withdraw from Putnam. The California pension funds have $1.5 billion invested in Boston-based Putnam.

Putnam did not immediately respond to calls by The Associated Press seeking comment Tuesday.