AT&T Inc. was downgraded by Moody’s Investors Service, citing a more than $180 billion debt load it estimates the wireless carrier will have after acquiring Time Warner Inc.

The purchase made the company the most indebted in the U.S., excluding financial companies. AT&T’s debt load will force it to refinance large amounts of debt every year, "making the company beholden to the health of the capital markets," Moody’s said as it lowered the company’s unsecured debt rating one level to Baa2, two levels above speculative grade.

Ratings downgrades can translate to higher borrowing costs for companies over time. AT&T was already the biggest U.S. corporate borrower outside of the financial system, with around $163 billion of debt as of the end of March. That figure rose after the $85 billion acquisition that closed on Thursday.

The company’s borrowings will be around 3.7 times a key earnings measure known as Ebitda, or earnings before interest, taxes, depreciation and amortization, by the end of this year, Moody’s said on Friday. Moody’s expects that figure to drop toward 3.5 times over the next 12 to 18 months.

A judge cleared AT&T’s takeover of Time Warner earlier this week after the Justice Department had sued to block it on antitrust grounds. Soon after that, Comcast Corp. bid $65 billion for 21st Century Fox Inc.’s entertainment assets, a long-awaited offer that is also expected to hurt Comcast’s credit quality.