It also said Trump, in granting Buyer a "full, complete and unconditional pardon", was acting on the "advice and recommendation" of 52 current and former members of the US Senate and House of Representatives listed in the proclamation.
Buyer served in the House as a Republican from Indiana between 1993 and 2011 before working as a corporate consultant.
He was found guilty in March 2023 on four counts of securities fraud, and was sentenced in September of that year to 22 months in prison.
Prosecutors said at trial that Buyer bought Sprint stock after learning from a T-Mobile executive that the telecommunications companies were in merger talks in 2018 and made illegal trades again the following year.
According to prosecutors, Buyer made more than $US100,000 from the Sprint trades and more than $US200,000 from buying stock in Navigant Consulting Inc before it was acquired by Guidehouse in 2019.
Buyer, who had served as one of the House managers in the 1999 impeachment trial of then-president Bill Clinton, took the stand at his own trial and denied trading on inside information.
Prosecutors sought three years in prison for Buyer in court filings, saying that he had abused his clients' trust and lied on the stand.
The US Supreme Court refused in May to hear Buyer's appeal of his conviction.
The Constitution gives a president broad power to grant pardons for federal crimes.
The pardons do not erase a recipient's criminal record but can be seen as act of mercy or justice.
with AP
