Alphabet, Inc. (NASDAQ:GOOG) (NASDAQ:GOOGL) and the U.S. Department of Justice are set to present closing arguments on Monday in a trial to determine if Google's advertising technology constitutes an illegal monopoly.

The Details: The DOJ alleges Google maintains a monopoly in "open-web display advertising" by dominating all aspects of the marketplace with a funnel of technologies that match online publishers to advertisers as well as controls the ad exchange market, which matches the buy side to the sell side.

"One monopoly is bad enough. But a trifecta of monopolies is what we have here," Justice Department lawyer Julia Tarver Wood said during her opening statement.

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Google says that the DOJ's case is focused on a narrow niche of digital advertising and that the company's market share of 25% has been decreasing as competition has increased in the space.

According to the AP, court documents show that Google argues the government's case "boil(s) down to the persistent complaints of a handful of Google's rivals and several mammoth publishers."

The case is being heard by U.S. District Judge Leonie Brinkema, in Alexandria, Virginia, who is expected to decide the case and issue a written ruling by the end of the year.

What Else: A District of Columbia judge, in a separate case, ruled in August that Google's search engine business does constitute a monopoly. The DOJ presented its proposed remedies last week, which included the requirement for Alphabet to divest Google Chrome, the internet's leading browser with over 60% market share globally.

Other proposals included forcing Google to share search data with competitors, and ending default search agreements, which make Google the automatic search engine on devices and web browsers like Apple's Safari.

"Google's unlawful behavior has deprived rivals not only of critical distribution channels but also distribution partners who could otherwise enable entry into these markets by competitors in new and innovative ways," the DOJ said in a statement.

The judge is expected to deliver a final decision in that case next summer.

Price Action: According to Benzinga Pro, Alphabet shares are up 1.92% at $167.92 at the time of publication Monday.

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