Attorney General Lisa Madigan announced her opposition Thursday to a proposed merger between Tribune Media Company and Sinclair Broadcast Group.

If the merger goes through, the company would own or operate more than 200 stations nationwide — including Tribune-owned WGN-Channel 9, according to a statement from Madigan’s office.

Madigan and attorneys general from Maryland, Massachusetts and Rhode Island filed comments with the Federal Communications Commission opposing the merger, arguing it would decrease consumer choice and the diversity of voices in the media marketplace.

Tribune Media agreed to a $3.9 billion sale of the company to Baltimore-based Sinclair Broadcast Group in May. Tribune shareholders filed a lawsuit to halt the sale in July, but voted to approve the sale three months later.

Tribune Media has 42 TV stations and WGN radio, and Sinclair owns 173 stations and other properties such as the Tennis Channel, according to TVNewsCheck.com.

The merger would make the new company the largest television broadcast company in the country and allow it to reach 72 percent of households in the country, exceeding a 39 percent cap on national audience reach, according to Madigan’s statement.

Further, Sinclair was relying on the “outdated” UHF Discount Rule to calculate its national audience reach, she argued.

The FCC voted to restore the rule in April, which allows companies to discount the reach of their UHF stations by half. Madigan argued that the rule does not take current technology into account.

Madigan urged the FCC to at least delay consideration of the merger until the D.C. Circuit Court completes its rule of the UHF Discount.