Japan's Prime Minister Shinzo Abe ordered an earlier review of the biggest pension fund's portfolio, health minister Norihisa Tamura said, amid speculation the fund is already buying more stocks. Tamura will ask the 128.6 trillion yen (HK$9.72 trillion) Government Pension Investment Fund to work on an overhaul of its investments, he said in Tokyo. Abe urged the changes to be announced in September or October, according to a Nikkei newspaper report. "The push to move the changes forward is good for the market," said Masaru Hamasaki, a Tokyo-based senior strategist at Sumitomo Mitsui Asset Management. "Revamping the allocations three months after the pension review came out will be quite a tight schedule, but if the prime minister has asked for this I think they'll do it by then." Investors are watching for Japan's cautious retirement-savings managers, led by the fund, to shift into shares as the Bank of Japan spurs inflation that risks eroding the value of bonds. The Topix index of equities slipped 5.3 per cent this year as of last week, adding pressure on Abe to prove his policies can spur a sustained economic recovery. Trust banks, which often buy and sell on behalf of pension investors, are putting the most money into local stocks in five years as foreigners sell, fuelling speculation that the fund is already buying. The fund may change its strategy in August and putting 20 per cent of its assets into local stocks would not be too much, Yasuhiro Yonezawa, who heads its investment committee, told the Nikkei this week. That compares with a current target of 12 per cent. Trust banks made 250 billion yen in net purchases of Japanese equities last week, according to data from the Tokyo bourse. That was the most since the period ended March 27, 2009. The banks have added money to the stock market for five consecutive weeks as the Topix index climbed 2.7 per cent and foreigners reduced holdings by 83 billion yen during the period. "Given that it's the biggest net purchase since stock prices plummeted during the financial crisis, you'd have to speculate that the fund or corporate pensions were doing the buying," said Shoji Hirakawa, chief equity strategist at Okasan Securities. "It's likely the fund is doing what it can to prepare for allocation changes. The market was expecting them to buy next fiscal year, but it looks like they're already doing it." Trust banks have bought a net 574 billion yen of Japanese shares this year, while foreign investors sold 1.4 trillion yen, the TSE data shows. That contrasts with 2013, when Topix's 51 per cent surge was accompanied by record foreign buying and the banks sold four trillion yen of shares. The Topix slumped as much as 13 per cent this year up to an April 14 low as the yen strengthened and investor optimism about Abe's revival strategies waned. The equity gauge has rebounded 8.8 per cent from that low as of Thursday. It remains the worst performer among developed markets.