General Motors Corp. suspends trading of its stock by executives and directors of the company, citing increased demand as shares plunged to a 54-year low Monday.

In a regulatory filing today, GM says all registered common shares of the company’s stock available under employee-benefit plans have been issued.

“This suspension is the result of recent unexpectedly high demand among the plans’ participants due to increased employee interest and a lower market price for the Common Stock,” GM says in a letter to executives and directors filed with the Securities and Exchange Commission. “The demand significantly exceeded the usual volume and exhausted the supply of registered stock more quickly than the administrators of the plans foresaw.”

Typically, the plan administrator would provide 15 days’ notice to investors.

Other employees may continue to sell GM stock or trade it for other investment options contained in the purchase plans, the filing says.

GM says it expects the blackout to continue until Nov. 9, when it files a request to sell additional shares.

GM’s stock plunged alongside the broader market yesterday, losing $1.25, or 12.8% to close at $8.51 after a proposed government bailout for struggling Wall Street firms failed to pass through Congress. It recouped some of that loss today, rising 94 cents, or 11.1%, to $9.45 before the closing bell. Shares of GM’s stock have traded between $43.20 and $8.51 over the last 52 weeks.