When the largest publisher in the country, Penguin Random House, struck a deal in the fall of 2020 to acquire its rival Simon & Schuster, publishing executives and antitrust experts predicted that the merger would be scrutinized by government regulators.

The number of major publishing houses would be reduced from five to four as a result of the merger. One analyst said it could create the Big One and the other three.

Stephen King, who was called by the government to testify in the trial, said in an email that such a shift could impact smaller publishers, authors, and eventually the books that reach readers.

The harder it is for independent publishers to survive is due to the consolidation of publishers. Good writers are starting out in that area.

The Biden administration tried to block the sale as part of its new and more aggressive stance against corporate consolidation. The trial will begin on Monday at the United States District Court for the District of Columbia.

A parade of publishing executives were called to testify. They include the chief executives of Penguin Random House and Simon & Schuster, as well as executives from other publishing houses and literary agents.

This is what we know about the case.

The merger would create a monopsony, according to the Justice Department. A monopoly is a seller with too much power over consumers. The government says that the suppliers are authors of books that will be top sellers, and that they get advances of more than $250,000.

There would be less competition for the biggest books if there were fewer big publishers. Advances paid to their authors would be lowered. Fewer authors will be able to earn a living from writing because of this.

The acquisition would increase competition in the industry and benefit both authors and readers according to the company.

The deal will give Simon & Schuster's authors access to Penguin Random House's distribution networks, which are generally considered the best in the business. A combination of the two companies will allow it to pay authors more and encourage other publishers to increase their offers.

The publishing industry is more than just the Big Five, as other publishers include Amazon and Disney. The government's argument about competition and author pay exaggerates the role auctions play when publishers are buying manuscripts.

Simon & Schuster will be able to bid against other Penguin Random House imprints, so authors will still have a lot of potential buyers.

A merger between two of the biggest publishing companies in the US would have a profound impact on the business and culture of publishing.

Like Hollywood, the book business has become reliant on blockbusters for profits, and companies will gamble enormous sums of money to buy books by brand-name novelists like John Grisham, or from celebrities and public figures.

The biggest publisher in the US is Penguin Random House, which has more than 90 imprints. Simon & Schuster has about 1,000 titles a year and will gain if the merger happens.

A disproportionate percentage of the top-selling books would be produced by the combined company. Simon & Schuster's books made up 11 percent of the top 100 best-selling print books last year.

Simon & Schuster would give up its distribution business for a network of smaller publishers in exchange for Penguin Random House gaining its printing, shipping and distribution capabilities.

As other publishers bulk up to compete with an even more massive rival, the merger could lead to further consolidation in the industry.

The collapse of the deal would be costly for the company. If the deal doesn't close, Paramount Global will have to pay Penguin Random House a fee of $200 million.

The company would be in a state of limbo. Evidence will be presented at the trial that will show whether or not Simon & Schuster will be sold or not.

It is not clear if another publishing house would want to risk the scrutiny of regulators by making a bid. Publishing Insiders worry that a private equity firm buying the company will lead to huge cuts to staff and fewer titles at Simon & Schuster.

The government may be able to mount more antitrust cases targeting the effects of corporate concentration on how much workers are paid.

A group of progressive academics, lawyers and economists argue that narrowing the number of employers has a negative effect on pay. The government's case will show how things go in court.

A group of mixed martial artists have been pursuing a class-action lawsuit against the Ultimate Fighting Championship for a long time. The U.F.C. denies that it is able to keep wages down. The merits of the case have not been considered despite a court ruling that the fighters could proceed as a group.

The administration has been praised for its aggressive approach to competition policy.

The Federal Trade Commission was encouraged to focus on the way that concentration can harm workers by President Biden's executive order. He wanted the agency to look at rules that make it hard for workers to take better job offers and to stop employers from sharing pay information in order to bring down wages.

Novel legal theories have been tried in court. The F.T.C. filed for an injunction to stop Meta from buying a virtual reality studio. The United Health Group's purchase of a health tech company was challenged by the Justice Department. It is not known how the courts will respond to these efforts.