Plug Power Inc (NASDAQ:PLUG) stock rallied more than 3% on Monday and went up another 4.38% on Tuesday to $4.67. But short interest in the stock has been rising this month after a slight decline in August. According to Nasdaq, 37.26 million Plug Power shares were sold short as of September 15, the latest date for which data is available.

Plug Power Inc Short Interest Spikes

Why is Plug Power stock soaring?

That’s a 3.7% increase from 35.93 million shares on August 29. Notably, short interested in Plug Power stock had fallen from 38.2 million to 35.93 million shares between August 15 and August 29. Based on the current average daily trading volume of 7.41 million shares, it will take short sellers a little over five days to close their positions.

Yesterday, Plug Power shares jumped after the company’s marketing department published a blog post, painting an optimistic picture of its business. Plug Power said material handling customers across North America had begun to realize the value of its fuel cell solutions. Customers who had initially opted for its GenKey are now going for its complete solution that includes GenKey fuel cells, onsite installation of its GenFuel hydrogen fuel cell infrastructure, storage and GenCare maintenance.

Plug Power helping automakers enjoy superior benefits

The Latham, New York-based company has supplied its GenKey and GenDrive fuel cell solutions to auto giants like BMW, Volkswagen, Honda, and Mercedes-Benz. The company claimed that these automakers are now enjoying “superior benefits and lower operational costs.” Plug Power said its fuel cell systems boost the amount of time forklifts are able to run compared to the ones that run on lead-acid batteries.

Last week, Plug Power entered an agreement with M&T Bank to offer financing services to its customers. It will help first-time buyers ease their transition from a diesel- or battery-powered equipment to fuel cell powered machines. Plug Power CEO Andy Marsh believes it will boost the company’s revenue. He expects the company’s FY2015 revenues to soar to $130 million, beating the consensus estimate of $126.37 million. For the current year, the company forecasts revenue of more than $75 million.