First, Sbarro. Now, Quiznos.

Quiznos has filed for bankruptcy protection, five days after the Sbarro pizza chain did the same.

Executives at the restaurant chain, known for its toasted sandwiches, agreed to a restructuring plan that will reduce its debt by more than $400 million, the company said in a statement Friday.

All but seven of Quizno's 2,100 restaurants in the United States and 30 other countries are independently owned franchises, and will remain open and operating as usual.

Quiznos once had more than 5,000 stores and could have threatened rival Subway's hold on the sub market. But now, Subway has nearly 20 times the number of stores, with about 40,000 locations in 100 countries.

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Quiznos CEO Stuart Mathis said the company will take action to help increase sales and profits for its franchise owners going forward. It will look to reduce food costs, invest in local advertising and, in some circumstances, make loans available for restaurant improvements.

The Denver-based company said it has lined up $15 million from investors to help keep the business running during the bankruptcy.