Blockbuster Inc., the nation’s largest movie-rental chain, posted a $491.4 million third-quarter loss as the elimination of most late fees continued to chip away at revenue and the growth of the company’s online service stalled.

Executives said Blockbuster would cut spending and raise at least $100 million through a private placement of convertible preferred stock.

In a filing Tuesday with the Securities and Exchange Commission, Blockbuster said “a very large majority” of its assets already were pledged as collateral on loans and that trade creditors were imposing stricter terms.

The company said it could be forced into bankruptcy protection if a new credit agreement with lenders doesn’t become effective or if lenders recall loans because of failure to meet debt covenants.