April 24 (Bloomberg) -- Thielert AG, the German aircraft- engine manufacturer that announced a share sale to increase liquidity this month, plunged as much as 81 percent after dismissing top managers and saying investors no longer support a reorganization plan.

The shares tumbled as much as 1.64 euros, or 81 percent, to 39 cents. Thielert closed at 43 cents, valuing the company at 9.11 million euros ($14.3 million), a loss of 79 percent from the previous close. The stock has declined 97 percent this year.

Germany's financial regulator BaFin is looking into Thielert shares ``as a matter of routine'' to inspect whether there may be signs of insider trading, the agency's spokeswoman Anja Neukoetter said in an interview today.

Chief Executive Officer Frank Thielert and Chief Financial Officer Roswitha Grosser were dismissed by the supervisory board amid a preliminary probe by the Hamburg prosecutors' office into alleged reporting errors made between 2003 and 2005, the Hamburg- based company said in a statement yesterday.

Thielert and Grosser aren't available for interviews, Caroline Vonderfelde, a spokeswoman for the company, said by telephone today.

The Hamburg prosecutors' office wasn't immediately available to comment.

Thielert said on April 10 it faces an ``urgent'' liquidity crisis and it needs as much as 38 million euros to cover a shortfall this year. The company said that investors who had previously supported reorganization are no longer prepared to provide the necessary funds as part of the plan to sell shares.

``Under these circumstances a bankruptcy is becoming more and more likely,'' said Frank Schneider, an analyst at alpha Wertpapierhandel in Frankfurt, in a telephone interview today.

-- With reporting by Karin Matussek in Berlin and Stefanie Haxel in Frankfurt. Editors: Angela Cullen, John Kohut.

To contact the reporter on this story: Henrietta Rumberger in Frankfurt at hrumberger@bloomberg.net.

Last Updated: April 24, 2008 11:53 EDT