Probers Subpoena American Express and Salomon Bros.

American Express and the investment firm of Salomon Bros. said Friday that they had been served with subpoenas by the Securities and Exchange Commission in connection with allegations that the stock of Fireman’s Fund, an American Express subsidiary, had been manipulated in advance of a secondary public offering of its stock.

The allegations were part of the SEC’s civil charges Thursday against Boyd L. Jefferies, the Los Angeles stockbroker who admitted that he had entered into illegal stock-trading arrangements with stock speculator Ivan F. Boesky. Jefferies resigned from the brokerage firm he founded and said he would plead guilty to two federal felony counts.

Fireman’s Fund Identified

The SEC’s complaint had charged that Jefferies agreed in 1986 to heavily trade the shares of an unidentified company one day in advance of a public offering of its stock by its parent, which was also unidentified in the SEC papers. Jefferies was said to have agreed to undertake the trading at the behest of a client apparently affiliated with one of the underwriters of the issue.

Sources confirmed that the issue involved was American Express’s offer in March, 1986, of shares in Fireman’s Fund, the insurance company it controlled. The stock issue was jointly managed by American Express’s Shearson Lehman Bros. unit and Salomon Bros.

In its statement, American Express said it received subpoenas Thursday for itself and for Shearson. The subpoenas “relate also to transactions with Jefferies & Co. and others,” American Express said.

Salomon, which took pains to note that “Shearson Lehman was the lead manager and ran the books for the offering,” said it received its subpoena Friday.