Shares of mobile phone maker Palm tumbled on Friday on questions over its ability to survive in a tough market dominated by Apple, Google and Research in Motion.

Its shares fell 19 percent in early Nasdaq trading to their lowest level in more than a year after the company warned on Thursday that revenue for the current quarter would be far below Wall Street's expectations, amid tepid demand for its smartphones.

In the third quarter, the maker of the Pre and Pixi shipped 960,000 units to carriers, but shoppers only purchased 408,000. It sees fourth-quarter revenue of less than $150 million, one-half of the $306 million expected by analysts surveyed by Thomson Reuters I/B/E/S.

As a result, several analysts cut their price targets for Palm shares, and Kaufman Bros analyst Shaw Wu cut his rating on the shares to "sell" from "hold".

"While we believe Palm has some value with its webOS (phone operating software platform)...we are unsure of the company's prospects as an ongoing concern," he said in a client note.

Four analysts tracked by Thomson One data now rank the stock at "sell" or "underperform", and 9 others rate the stock at "hold."

Canaccord Adams analyst Peter Misek, who has a "sell" rating, said Palm's troubles will likely accelerate as its partners question the company's solvency and withdraw their support.

"With what appears to be roughly 12 months of cash on hand, an accelerating burn rate, a complete lack of earnings visibility, and substantial debt and preferred equity, we no longer see any value in the company's common equity," he said in a note.

Palm has been the subject of chatter that it might be an acquisition target, with Microsoft Corp, Nokia and Dell Inc often mentioned as potential suitors. On a conference call with analysts, Palm chief executive Jon Rubinstein downplayed such talk.

Palm shares fell to $4.56 on Nasdaq, where it was the second biggest percentage loser so far on Friday, and also the second most active stock.