The decision by former National Lampoon Inc. Chief Executive Daniel Laikin to plead guilty to a charge that he helped manipulate the company’s stock price has closed the book on a troubled period in the entertainment company’s history.

Laikin last week pleaded guilty to one count of conspiracy in connection with a scheme to artificially inflate the stock of the West Hollywood-based company, which is perhaps best known for its stake in the “Animal House” and “Vacation” film franchises.

In exchange for Laikin’s plea, prosecutors agreed to drop a separate charge of securities fraud. The deal was announced Wednesday by the U.S. Attorney’s Office in Philadelphia, which investigated the case because a co-defendant worked in the area and some of the stock manipulation had taken place in that region.

After he was arrested in December, Laikin initially pleaded not guilty. His three co-defendants all pleaded guilty. Joseph Poluka, Laikin’s attorney, declined to specify why his client changed his mind.

“I can’t get into motivation,” Poluka told the Business Journal after last week’s guilty plea. “There were negotiations with the government that resulted in the plea that’s set forth.”

Prosecutors said that Laikin paid kickbacks to his co-defendants after they bought a large amount of National Lampoon stock in Laikin’s attempt to inflate demand for shares in the entertainment company.

When Laikin and his co-conspirators were arrested, the Securities and Exchange Commission de-listed the company from the American Stock Exchange; it currently trades as an over-the-counter penny stock.

With Laikin destined for a prison cell, National Lampoon will now likely continue to push forward with a reorganization started by Timothy Durham, a wealthy Indianapolis financier who took over the company when Laikin was arrested. Durham knows Laikin from their days together in Indiana, where Laikin was a homebuilder.

Durham did not return requests for comment Thursday. In the past, he told the Business Journal he wanted National Lampoon to focus on producing and distributing films, which was the company’s core business before Laikin took over and diversified.

Laikin tried to spread the National Lampoon brand across multiple platforms, buying up a series of college humor Web sites, and starting a radio station and even a book publishing arm. Now, Durham is trying to return the company to its roots in film-making.

Laikin is to be sentenced Jan. 13. He faces up to five years in prison, three years of supervised release and a $250,000 fine. His co-defendants face sentencing hearings later this year and early next.