Federal investigators are probing the business of block trading on Wall Street, examining whether bankers might have improperly tipped hedge-fund clients in advance of large share sales, according to people familiar with the situation.

The Securities and Exchange Commission sent subpoenas to firms including Morgan Stanley and Goldman Sachs as well as several hedge funds, asking for trading records and information about the investors’ communications with bankers, some of the people said. The Justice Department also is investigating the matter, some of the people said.