Ad tech firm Tremor Video's stock is cratering after its CEO suddenly quit

Ad tech company Tremor Video's CEO Bill Day has suddenly resigned after almost nine years in the role, without providing a reason.

Day's departure from company, which is effective immediately, was announced during the company's fourth quarter earnings.

Tremor's non-executive board chairman Paul Caine will take over in the interim. The company has hired executive search firm Heidrick & Struggles help look for Day's replacement. Day will continue as an advisor to the company and sit on its board of directors until June.

Caine said in a statement: "On behalf of the board, we applaud Bill for his significant contributions during his eight years of service with the Company, and we are grateful for his efforts in building our leadership position in the video advertising marketplace. We reached many important milestones during Bill's tenure and his expertise has guided the Company to a position of strength while setting us on a strong path for sustainable profitability and future growth."

Tremor did not immediately respond to a request for comment.

The company's stock was down more than 6% at the time of writing.

Tremor reported a 4% lift in revenue year-over-year to $53.8 million. Adjusted EBITDA (earnings before interest, tax, depreciation, and amortization was down 66% to $3.5 million. The company reduced its net losses from $0.4 million, from $2.4 million in the year-ago quarter.

Tremor, a video demand-side platform that recently expanded to offer a supply-side product for publishers, debuted on the New York Stock exchange at a price of $10 per share in June 2013. But like most public ad tech companies, the firm has experienced a tough time for investors and its stock is currently trading around the $2 mark.

In November last year, Tremor competitor TubeMogul was acquired by Adobe for $540 million.