Shares of Clean Energy Fuels Corp. fell 5.5 percent on Thursday after the company said it would distribute a renewable natural gas at some fueling stations, disappointing investors who had bid up the stock this week on the chief executive's Twitter promise of "big news."

Shares of the provider of natural gas for transportation were down 77 cents at $13.02 in afternoon trading on the Nasdaq.

On Monday, Clean Energy CEO Andrew Littlefair tweeted: "I promised big news this week and I'll deliver," sending his company's stock up a combined 8 percent over the following two days.

The stock gave back most of those gains on Thursday, however, when the Newport Beach, California, company said it would be the first to commercially distribute natural gas vehicle fuel made from waste streams, such as landfills, dairies and sewage plants, something it has been doing for some time.

"Today we found out what the news is: except that it's not actually news," Raymond James analyst Pavel Molchanov wrote to clients. "This represents a rebranding, pure and simple, of what the company has already been doing."

Clean Energy will market the fuel under the brand name "Redeem." It will be sold directly to fleets around the country and at 35 California public fuel stations for the same price as compressed natural gas.

Clean Energy sold 8.9 million gasoline equivalent gallons of renewable natural gas last year, according to a regulatory filing. It said in Thursday's statement that it plans to sell 15 million gallons of Redeem in its first year.