Lordstown Motors, a troubled electric truck start-up, raises up to $400 million.

Lordstown Motors, a struggling electric pickup truck company, said Monday that it had reached a deal with an investment firm to raise $400 million over three years.

The investment firm, Yorkville Advisors, has agreed to buy up to $400 million of Lordstown’s shares, which would provide badly needed cash to a company that this summer said it could go out of business without raising more money.

The deal is potentially quite lucrative to Yorkville because it will buy the stock for at least $7.48 a share, the closing price on Friday. If Lordstown stock rises, the hedge fund stands to make a profit.

Yorkville agreed that it would not bet against Lordstown’s stock. Lordstown also agreed to give Yorkville 371,000 shares, which are worth nearly $3 million based on the current stock price, for agreeing to the deal.

Once hailed by former President Donald J. Trump as a savior of manufacturing jobs in Ohio, Lordstown has struggled to produce vehicles while spending hundreds of millions of dollars. The company is also being investigated by the Securities and Exchange Commission and the Justice Department.

Lordstown, which acquired a former General Motors factory in Lordstown, Ohio, went public in October by merging with DiamondPeak Holdings, a special purpose acquisition company led by a wealthy Wall Street real estate investor.

SPACs raise money by selling stock before they have any assets, and then go shopping for a business. They offer the companies they merge with a way to list on the stock market with less disclosure and scrutiny than is typical in an initial public offering.

The S.E.C. is investigating whether the company and its founder, Steve Burns, who resigned as chief executive in June, overstated claims about interest from commercial buyers in its electric truck, the Endurance. Federal prosecutors are also investigating the company’s preorder claims and its merger with DiamondPeak.

The company, which has beefed up its public relations operation in recent weeks, is being represented by lawyers from Sullivan & Cromwell, a big New York law firm, in connection with the investigations. Mr. Burns has hired two lawyers from Simpson Thacher & Bartlett, another big New York firm.

Yorkville, which specializes in investing in small companies, is not without its own controversy. In 2012, the S.E.C. accused the firm of misvaluing its assets to hide losses from investors. But in 2018, a federal judge dealt a big blow to the S.E.C. by dismissing most of the civil fraud claims against Yorkville. Regulators and Yorkville ultimately agreed to dismiss the matter.

Lordstown’s stock price has tumbled from a peak of almost $31 in February and is now trading at less than the $10 price that DiamondPeak sold shares at during its initial public offering. The stock was down 2.5 percent at the close of trading on Monday.