The NASDAQ stock exchange shot another de-listing warning across NMT Medical Inc.’s (NSDQ:NMTI) bow, after an August boardroom shuffle left it without enough directors to man its audit committee.

The Boston-based company revealed the warning in a filing with the federal Securities & Exchange Commission.

The company’s troubles began June 17, when it reported that its flagship StarFlex device failed to meet the primary endppint of a clinical trial. The news sent NMTI’s stock price on a 79 percent dive that day; shares have averaged under 50 cents since then, a far cry from an all-time high of $24.56. Trying to regroup, NMT said it would "tightly manage expenses, preserve cash, evaluate financing alternatives and adjust our operating plan accordingly," as it waits for the final results of the Closure I trial to be completed in November, according to its second-quarter earnings release. In August, the company’s poor stock performance drew a first de-listing warning from the NASDAQ exchange. Later that month, former CEO Frank Martin and chairman James Mahoney stepped down, with COO Richard Davis taking the helm as chairman, president and CEO.

NMT has either until its next shareholders meeting or Aug. 25, 2011, to bolster its audit committee and regain the exchange’s good graces. The company hasn’t decided how it will respond to the warning, according to the filing, but Davis told MassDevice in an email that, “Currently it is the plan of the company to look to add a board member that will help it get back into compliance with the ‘financial expert’ aspect of the listing qualifications.”