The cumulative value of shares the Bank of Japan has bought from commercial banks under a special program to ease their exposure to falling share prices came to 527.1 billion yen as of Monday, the BOJ said Thursday.
The program calls for the central bank to try to buy a combined 2 trillion yen by Sept. 30.
The updated value represents an increase of 144.8 billion yen over the corresponding amount as of Jan. 31, the central bank said.
The increase was the sharpest since the central bank started the share-purchase program last November. The BOJ releases the cumulative value of its share-buying from banks every 10 days.
The combined value of the shareholdings unloaded by banks shot up during the 10-day period to Monday because major banks are scrambling to rid themselves of as many shares as possible prior to March 31 book-closings, observers said.
Unrealized losses could eat into banks' capital under revised accounting rules, which require banks to deduct some losses from profits.
Some ruling coalition officials are calling on the central bank to buy far more than the planned 2 trillion yen, but the BOJ has so far brushed aside these calls out of fears that increasing the limit could undercut the quality of its assets and give lawmakers an excuse not to embark on reform and deregulation policies.