FITCHBURG, Wis. — Promega Corp. and its founder are firing back at shareholders who sued the Wisconsin biotechnology company in 2016 for shareholder oppression.

The lawsuit filed by shareholders Nathan Brand and Ted Kellner alleges that company founder Bill Linton bullied shareholders in order to keep majority control of the company.

Shareholders said Linton’s business plan wouldn’t allow them to see a return on their investment until 2078.

Linton formed Promega in 1978 and has said he has a 100-year plan that includes keeping the business a private company.

The counterclaim alleges Brand and Kellner hatched a plot to take over the company and force Promega’s board to pay an exorbitant price for their shares, the Wisconsin State Journal reported.

Much of the information in the court filings was from e-mails and other correspondence Brand and Kellner turned over during the lawsuit’s legal discovery process.

Court documents allege the group planned to make an offer to the board to buy Promega at $625 a share, or a total of $1.25 billion, including $600 million of debt, at closing.

The counterclaim states that the shareholders’ plan would have left the business with a large debt that would have damaged its research and development efforts.

The counterclaim also alleges that Brand and Kellner planned to sell the business within five years, though they told other shareholders they wanted to help it prosper in Wisconsin.

Linton’s filing alleges Brand and Kellner “intentionally, willfully and maliciously” injured his reputation and profession and were “irrational, outrageous and in reckless disregard of Linton’s rights.”

James Southwick, the shareholders’ attorney, said they have no comment on the case. They have until Nov. 2 to respond to the counterclaims.

Promega sells 3,500 products used in research, drug discovery and DNA identification. It has more than 800 employees in the Madison area.