Robert Carr, 73, who also founded Heartland, was accused of repeatedly discussing the late-2015 merger talks with Katherine Hanratty, 65, whose relationship with him had begun in 2011.

Carr was also accused of having given Hanratty a $1 million check before the merger, with instructions to open a brokerage account and buy $900,000 of Heartland stock.

The SEC said Hanratty, whom it also charged, did what Carr asked, and sold her stock for a $250,628 profit in April 2016, four months after Atlanta-based Global Payments agreed to buy its smaller rival.

Hanratty, who co-owns a staffing agency, had repeatedly expressed concern to Carr about her finances, and after opening the brokerage account - which named Carr as the beneficiary - emailed him that "for the first time ever I feel a sense of relief knowing that I have some security," the SEC said.

Global Payments agreed on Dec. 15, 2015 to buy Princeton, New Jersey-based Heartland for $100 per share, a 17.5 percent premium, and more than 28 percent above where it traded on Dec. 9 before media began reporting a possible merger.

The SEC said Carr, of New London, New Hampshire, had bragged to his children and their spouses that a merger was in the works, and given Hanratty, of Watertown, Connecticut, a draft quotation for the press release announcing it.

"Love it," replied Hanratty, even as she suggested an improvement, the SEC said.

The SEC complaint filed with the federal court in New Haven, Connecticut, seeks civil fines, the recouping of illegal profit, and an officer and director ban for Carr.

Lawyers for the defendants did not immediately respond to requests for comment.

A lawyer for Global Payments declined to comment. The company in May sued Carr and Hanratty in the federal court in Trenton, New Jersey to recoup trading profits it said arose from Carr's alleged breaches of fiduciary duty.

The SEC case is SEC v Carr et al, U.S. District Court, District of Connecticut, No. 18-01135.

(Reporting by Jonathan Stempel in New York; Editing by Steve Orlofsky, Tom Brown and Richard Chang)

By Jonathan Stempel