CKE Restaurants (CKE), owner of the Carl's Jr. and Hardee's chains, agreed on Friday to sell itself to buyout firm Thomas H. Lee Partners for $928 million, underscoring the economic power of fast-food restaurants during tough economic times.

The deal values CKE shares at $11.05 in cash, representing a 24% premium over Thursday's closing price, and includes the assumption of $309 million of net debt. Shares of CKE, based in Carpinteria, Calif., soared in pre-market trading, They have gained 28% over the past year. CKE has 3,100 company-owned and franchised eateries across the country.

Having Thomas Lee as a corporate parent will help CKE better compete against rivals including McDonald's (MCD) and Burger King (BKC), which have gained market share as diners bypassed pricier casual-dining chains. In January, CKE posted a 6.4% decline in same-store sales (stores open more than one year), citing bad weather and continued high unemployment.

More Heat in the Kitchen

Boston-based Thomas H. Lee is no stranger to the food business: The firm and several partners acquired Aramark, which provides meal service to corporate cafeterias, colleges and universities, and sports stadiums, for $8.3 billion in 2006. It's also one of three co-owners of Dunkin' Brands, parent of Dunkin' Donuts and Baskin-Robbins.

Other fast-food chains are bound to feel the heat from the sale. While McDonald's fourth-quarter results showed an earnings rise of 23% year-over-year, Yum! Brands (YUM), owner of KFC, recently reported disappointing fourth-quarter results. And Wendy's/Arby's Group (WEN) shares are down 2.25% over the past year.

Given the premium CKE fetched, investors are going to pressure other fast-food operators to get them a return as good or better.