The Massachusetts pension board withheld a $75 million investment from Fidelity Investments on Monday, expressing doubts and concerns over how the mutual fund giant has responded to the government's investigation of its traders' improper trading practices, the Boston Globe reports.

While Fidelity has not been charged with any wrongdoing, regulators investigating the case are trying to determine if Fidelity traders gave more business to brokers who showered them with gifts and entertainment rather than to those brokers who offered the best prices on trades.

State officials say they are seeking more information on whether or not two investment accounts totaling nearly $700 million, which Fidelity manages for the state, were affected negatively by Fidelity traders' actions.

Officials are also disturbed that the commissions Fidelity pays brokers for trading stocks on the state account are 5 cents a share, almost twice the amount paid to other domestic stock money managers working for the state.

The pension board was going to split a $300 million high-yield account evenly among four other firms, including Fidelity. But after learning on Thursday that two of Fidelity's 16 traders, who were disciplined for violating its gift policies, are now on the high-yield trading desk, the board decided to keep Fidelity out. It said that Fidelity had not informed state officials about the two traders before it was asked about them.

Fidelity manages $352 million in high-yield debt for the state and $340 million in large-cap stocks.

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