ManTech International (MANT - Get Report) shares plunged after the company said changing government policies related to the company's personnel security investigation unit would result in a loss for the quarter.

Without providing immediate specifics, the company said in a press release Monday that its MSM personnel security investigation business would have additional losses due to new government policies.

As a result, ManTech said it couldn't reconfirm the second-quarter and full-year earnings guidance it gave May 26, when it lowered its second-quarter expectations to 13 cents to 15 cents a share and its full-year guidance to $1.17 to $1.21 a share.

Analysts had forecast second-quarter earnings of 13 cents a share and full-year earnings of $1.17 a share.

Shares of ManTech were recently down $4.07, or 25.1%, to $12.17.