They bought a total of 2.8 million shares, the most in at least 60 days, in companies including Sumitomo Mitsui Construction Co. and automotive retailer Yellow Hat Ltd.
Activist investors took advantage of Japan’s stock rout earlier this month to boost their holdings, seeking more influence over companies ranging from drug makers to construction firms.
Funds affiliated with prominent Japanese activist investor Yoshiaki Murakami, Tokyo-based Strategic Capital Inc. and the UK’s Nippon Active Value Fund Plc were among funds that added to their holdings during the Aug 5 selloff, according to filings made to Japan’s Ministry of Finance.

