Shares of Green Mountain Coffee Roasters lost almost half their value on Thursday, as management lost the confidence of Wall Street after the company cut its outlook and again badly missed sales estimates.


Short-sellers have been questioning Green Mountain’s accounting for months. They said the financial results, reported late Wednesday, added weight to the contentions of the hedge fund manager David Einhorn and others that the company had been inflating sales and that its high-growth days were over.


A Green Mountain spokeswoman on Thursday declined to answer questions on its accounting or to give any comment.


Green Mountain shares fell 48 percent to close at $25.87 on Nasdaq on Thursday, and hit one of their lowest points in almost two years. The stock hit a lifetime high of $115.98 in September.


The company, which makes Keurig coffee brewers, cut its financial forecast for the year on Wednesday and warned of slowing growth after demand for its K-Cup coffee refills fell far short of expectations in the March quarter.


Green Mountain has also been facing an inquiry by the Securities and Exchange Commission into how it recognizes some revenue and its relationship with a vendor.


“We have diminished faith in Green Mountain’s forecasting abilities following misses in two of the last four quarters,” William Chappell at SunTrust Robinson Humphrey said in a note.


Also troubling to some analysts was that Green Mountain’s chief executive, Lawrence J. Blanford, could not explain why demand was less than expected.


“We’ve just got a lot of moving parts, and I think we continue to increase our capability but it’s gotten even more difficult to put our arms around,” Mr. Blanford said during a conference call with analysts on Wednesday.