The TSP’s governing board has decided to place new limits on the number of interfund transfers—movements of money among the program’s investment funds—in response to especially frequent trading activity by a minority of investors that is raising overhead costs for all investors. Starting in the spring, investors will be allowed only two interfund transfer orders a month, with a third allowable if a mistake was made. Until bringing a new computer system online in 2003, the TSP allowed only one interfund transfer a month; since then, interfund transfers can be made every business day, and several thousand investors have been highly active—especially, lately, with trading in the international stock fund, whose transaction costs are the highest of the TSP funds. Officials said that until the computer system can be changed to accommodate the new policy, those investors will be asked to cut back their activity under threat of being allowed to request transfers only through the mail. They note that many mutual funds impose restrictions on transaction frequency, for example by charging fees for selling an investment that had been held for less than a certain period of time.