TOKYO, May 28 (Reuters) - Shares of Nomura Holdings fell slightly in early Monday trade after Japan's largest broker was linked to a second insider trading case involving a fund management arm of Sumitomo Mitsui Trust Holdings
Nomura's stock was down 0.4 percent at 259 yen as of 0009 GMT, underperforming the benchmark Nikkei average, which gained 0.5 percent.
Shares of Sumitomo Mitsui Trust Holdings, which sources with knowledge of the matter said would be subject to its second fine for insider trading in two months, fell 0.5 percent.
The Securities and Exchange Surveillance Commission (SESC) found that a fund manager in the Sumitomo Mitsui group sold shares of Mizuho Financial Group with knowledge of the lender's stock offering in 2010 before it became public, the sources told Reuters on Saturday.
The SESC believes an employee of Nomura, which was an underwriter on the 780 billion yen ($9.8 billion) Mizuho offering, provided that tip-off, according to the sources, who were not authorised to speak to media about the matter.