“Cash Burn Rate,” used to value companies with little or no revenues, was a popular term in the dot-com era. The burn rate is the amount of cash that is being used up over time. From this, analysts would calculate the period until a business would run out of cash, assuming the current operating costs continues.

Read American Companies Running Out of Cash

Running a business just with cash on hand cannot continue forever if at some point losses cannot be turned into profits. Eventually, cash must flow into a business at a greater rate than it leaves or the business will face extinction. That is even true if a company sells assets, which will eventually run out, too.

In the early stages of the Internet, revenue generation was a key problem as many websites did not have a tangible product, let alone profits, to support the multi-million or billion dollar valuations. Many of these companies indeed ended up in the graveyard when the cash ran out and the dot-com bubble burst.

Fast forward a few years and Wall Street once again faced a similar situation. The recession, which officially started in 2007, has placed financial strains on many businesses. When revenue declines are not met with the same reduction in spending, they can lead to negative cash flow. Companies can take short-term measures to handle cash flow problems until conditions improve through borrowing or equity issues. However, poor market conditions make it harder for troubled companies to borrow. Businesses, even large ones such as Eastman Kodak and American Air parent AMR, without the capital to make it through an extended stretch of weakened economic conditions, have fallen into bankruptcy.

With that in mind, we wanted to see which companies today are burning through cash at a rate that should concern shareholders.

Capital IQ provided 24/7 Wall St. with a list of 38 non-financial companies that had a negative burn rate. That is, cash from operations in the latest 12 months was negative at these companies. Capital IQ calculated the monthly burn rate by dividing this annual number by 12. Next, the number of months before cash runs out was calculated by dividing the cash, cash equivalents and short-term investments by the monthly burn rate. We took a closer look at each company to find out if the numbers were misleading or if the company could indeed be facing serious liquidity problems.

Here are the seven companies that would run out of cash during the next 18 months based on their last 12-month burn rate.