What happened

It's Friday, and with the S&P 500 up a solid 1.5% as of 1:55 p.m. ET, it's starting to look like the stock market is going to end the day -- and the week -- on another high note. But not all stocks are so lucky.

Striking a discordant note from the market's enthusiasm today is space tourism pioneer Virgin Galactic (SPCE -1.09%), shares of which are falling 5.2% in response to a big downgrade to "underperform" from analysts at investment bank Bernstein.

So what

As StreetInsider explains today, Bernstein just cut Virgin Galactic one notch to the equivalent of a sell rating and cut its price target on the shares to $4, implying roughly 33% downside in the stock. "We now have less confidence in the success of this business," states Bernstein bluntly, criticizing Virgin Galactic for continually pushing back plans to begin commercial space tourism flights, and warning that with paying flights not expected to begin before the second quarter of 2023 at the earliest, there is now only "limited potential for positive near-term catalysts."  

Worse, Bernstein sees clear potential for negative catalysts if Virgin Galactic postpones the resumption of test flights, and the resultant postponement of commercial flights, even further than it already has.

Now what

Simply put, the longer Virgin Galactic remains in business, spending money on development but collecting no revenue to offset its development costs, the more cash this company will burn. Indeed, according to data from S&P Global Market Intelligence, Virgin Galactic's cash burn rate has accelerated every year it's been in business -- and still with very little revenue to show for it.

Granted, with more than $900 million in the bank and the ability to sell more shares to raise more cash as needed, Virgin Galactic still probably has another three years or so before investors need to worry about insolvency risk. But even if Virgin Galactic, the company, isn't necessarily going away anytime soon, that doesn't necessarily mean that Virgin Galactic, the stock, will be going anywhere fast.

Until this company proves it's got a viable business plan, Virgin Galactic stock is likely to remain dead money -- and Bernstein is right to pan it.