Mednax Inc. said Starboard Value LP has nominated a majority slate of directors for the company's board.

The activist investor is also urging Mednax to sell the entire company or part of itself, The Wall Street Journal reported, citing people familiar with the matter.

In a Dec. 11 Form 8-K filing, Mednax said it already met with Starboard as a new shareholder. The company noted that it welcomes a constructive dialogue with the investor.

S&P Global Ratings in October downgraded the company's long-term issuer credit rating to BB from BBB- on weak performance.

The same month, the company agreed to sell its MedData LLC unit to private equity firm Frazier Healthcare Partners to focus on its core physician services business and significantly reduce leverage and future capital expenditures.

Sunrise, Fla.-based Mednax has a market capitalization of $2.06 billion.