New York ? An assistant to Martha Stewart’s stockbroker pleaded guilty Wednesday to a misdemeanor charge that he took a payoff to keep silent about an alleged insider stock tip given to Stewart.

Douglas Faneuil, 26, pleaded guilty as part of a deal to testify against Stewart and others who allegedly sold shares of ImClone Systems Inc. last December, if she is ultimately charged in the case. The charge is receiving money or other valuables “as consideration for not informing.”

Stewart dumped nearly 4,000 shares of ImClone just before the stock price plunged on news the Food and Drug Administration would not review its highly-touted cancer drug, Erbitux.

Court papers did not identify the “tippee” who received the insider information, but all the details clearly point to Stewart.

Merrill Lynch, where Faneuil worked, handled Stewart’s sale of nearly 4,000 ImClone shares.

Faneuil’s lawyer, Marvin Pickholz, was asked outside court if the “tippee” was Stewart, and answered: “If you guys read this information and you can’t fill in the blanks, you’re in serious trouble.”

Faneuil admitted during his plea that he had withheld the truth from Securities and Exchange Commission investigators and FBI agents when interviewed about the trading activity.

Prosecutors are trying to build a criminal case against Stewart for allegedly receiving insider information. She and her friend Sam Waksal, ImClone’s founder and ex-CEO, shared a Merrill Lynch broker, Peter Bacanovic, who was Faneuil’s boss.

In the court papers, prosecutors said the tip to the “tippee,” either directly or indirectly, came from Bacanovic.

Martha Stewart’s spokeswoman Allyn Magrino declined to comment on Faneuil’s plea.