ComScore, the company that competes with Nielsen in measuring TV and online audiences, revealed Monday it is looking into “potential accounting matters.”

Shares plummeted as much as 35% after the marketing data company said in a press release that it would delay the release of its annual report and suspend plans for a $125 million stock buyback.

The Reston, Va.-based company does not expect to be able to wrap up an internal review of the unspecified “potential accounting matters” before March 15, which marks the end of a 15-day extension window to file its annual report for 2015 with the U.S. Securities and Exchange Commission.

ComScore also said “out of an abundance of caution” it will suspend the share repurchase program that it announced last month and that the buyback will be “reevaluated” once the internal review is complete.

The company’s audit committee is conducting the internal review. ComScore said it learned about the potential accounting issues last month, just a few days after the company released its fourth-quarter financial results, which showed record revenue for the quarter and a year-over-year bump of 8%.

The announcement on Monday morning sunk ComScore’s stock to its lowest levels of 2016 and the company’s shares are now down more than 45% over the past 12 months.

Last fall, ComScore announced plans to merge with media tracking service Rentrak in an effort to take on Nielsen as an industry source for cross-platform audience measurement. As Variety noted on Monday, ComScore CEO Serge Maata promised last month that the company would roll out a new cross-platform system to measure television audiences in time for this spring’s round of TV industry upfronts.