A technology research analyst who had taunted the government over its investigations of insider trading pleaded guilty on Wednesday to securities fraud charges, admitting that he had enticed employees of public companies to feed him insider information that he then sold to hedge funds and money managers as if they were from legitimate research.

The analyst, John Kinnucan, 55, entered the plea to charges of conspiracy to commit securities fraud and two counts of securities fraud in Federal District Court in Manhattan, agreeing to a plea deal with the government with sentencing guidelines that call for him to serve roughly four to five years in prison. The charges otherwise would have carried a potential prison term of up to 45 years. Sentencing was set for Jan. 15.

The calculation of the sentencing guidelines, the authorities said, includes extra time for obstruction of justice related to threats that Mr. Kinnucan made to prosecutors, F.B.I. agents and a cooperating witness during the investigation of Mr. Kinnucan and his company, Broadband Research, an investment research firm in Portland, Ore.

The government said Mr. Kinnucan made nearly 25 threatening telephone calls from December through February that contained repeated references to genocide, sexual violence and other violent acts. He specifically threatened physical harm to one female prosecutor, the government said.