There's no doubt that money can be made by owning shares of unprofitable businesses. For example, biotech and mining exploration companies often lose money for years before finding success with a new treatment or mineral discovery. But while history lauds those rare successes, those that fail are often forgotten; who remembers Pets.com?

So, the natural question for Seres Therapeutics (NASDAQ:MCRB) shareholders is whether they should be concerned by its rate of cash burn. In this report, we will consider the company's annual negative free cash flow, henceforth referring to it as the 'cash burn'. First, we'll determine its cash runway by comparing its cash burn with its cash reserves.

When Might Seres Therapeutics Run Out Of Money?

A company's cash runway is the amount of time it would take to burn through its cash reserves at its current cash burn rate. In March 2026, Seres Therapeutics had US$30m in cash, and was debt-free. Importantly, its cash burn was US$42m over the trailing twelve months. Therefore, from March 2026 it had roughly 8 months of cash runway. To be frank, this kind of short runway puts us on edge, as it indicates the company must reduce its cash burn significantly, or else raise cash imminently. The image below shows how its cash balance has been changing over the last few years.

How Is Seres Therapeutics' Cash Burn Changing Over Time?

In our view, Seres Therapeutics doesn't yet produce significant amounts of operating revenue, since it reported just US$1.1m in the last twelve months. As a result, we think it's a bit early to focus on the revenue growth, so we'll limit ourselves to looking at how the cash burn is changing over time. As it happens, the company's cash burn reduced by 51% over the last year, which suggests that management are mindful of the possibility of running out of cash. While the past is always worth studying, it is the future that matters most of all. For that reason, it makes a lot of sense to take a look at our analyst forecasts for the company.

Can Seres Therapeutics Raise More Cash Easily?

While we're comforted by the recent reduction evident from our analysis of Seres Therapeutics' cash burn, it is still worth considering how easily the company could raise more funds, if it wanted to accelerate spending to drive growth. Companies can raise capital through either debt or equity. One of the main advantages held by publicly listed companies is that they can sell shares to investors to raise cash and fund growth. By looking at a company's cash burn relative to its market capitalisation, we gain insight on how much shareholders would be diluted if the company needed to raise enough cash to cover another year's cash burn.

Since it has a market capitalisation of US$55m, Seres Therapeutics' US$42m in cash burn equates to about 77% of its market value. Given how large that cash burn is, relative to the market value of the entire company, we'd consider it to be a high risk stock, with the real possibility of extreme dilution.

How Risky Is Seres Therapeutics' Cash Burn Situation?

On this analysis of Seres Therapeutics' cash burn, we think its cash burn reduction was reassuring, while its cash burn relative to its market cap has us a bit worried. Considering all the measures mentioned in this report, we reckon that its cash burn is fairly risky, and if we held shares we'd be watching like a hawk for any deterioration.

Of course, you might find a fantastic investment by looking elsewhere. So take a peek at this free list of companies with significant insider holdings, and this list of stocks growth stocks (according to analyst forecasts)

This article by Simply Wall St is general in nature. We provide commentary based on historical data and analyst forecasts only using an unbiased methodology and our articles are not intended to be financial advice. It does not constitute a recommendation to buy or sell any stock, and does not take account of your objectives, or your financial situation. We aim to bring you long-term focused analysis driven by fundamental data. Note that our analysis may not factor in the latest price-sensitive company announcements or qualitative material. Simply Wall St has no position in any stocks mentioned.