$Alphabet-C (GOOG.US)$ $Alphabet-A (GOOGL.US)$ shares are moving lower in extended trading Tuesday following a report suggesting a bid to break up Google is on the table for the U.S. Department of Justice (DOJ).

What Happened: Bloomberg reported that the DOJ is considering a bid to break up Google after a federal judge ruled against Alphabet in an antitrust lawsuit related to the company's Search dominance last week.

The report indicates a push to break up Google would be the first attempt to dismantle a company for monopolization since regulators unsuccessfully attempted to break up Microsoft more than two decades ago. If the DOJ moves forward with the breakup plan, the Android operating system and Google Chrome are the most likely units for divestment.

The DOJ is reportedly exploring less severe options as well, including forcing the company to share more data with competitors in an effort to stop Google from gaining an unfair advantage in its AI products.

Regardless, people familiar with the matter said the government is likely to try to put an end to the type of contracts that were scrutinized in the recent case against Google.

Judge Amit Mehta ruled last week Alphabet's payments to make its search engine the default option on smartphone web browsers violated U.S. antitrust law by effectively blocking competition in the space. Regulators alleged Google maintained a monopoly on online search and related advertising through billions of dollars in payments to smartphone makers. Alphabet has said it will appeal that decision.

Google is the most-used search engine in the world with more than $300 billion in annual revenue. A forced breakup of Alphabet would be the biggest breakup of a U.S. company since AT&T was broken up in the 1980s.

GOOG Price Action: Alphabet shares were down 0.85% after hours at $164.52 at the time of publication.