The price/sales ratio measures the price of the stock based on its revenues. It is calculated on a per share basis by dividing the share price by the sales per share. A P/S below 1 is excellent. Depending on the type of company, a P/S of 1 to 2 is reasonable. A P/S of over 5 is usually unfavorable and means that the stock is very overpriced based on its sales.
Here are five stocks which have market caps of over $500 million, negative earnings, and very low revenues [and therefore extremely high P/S ratios]. Four out of five are biotech companies, so even with bad financials, they can still spike up from successful clinical trials and new drug approvals.
Caution for potential short sellers: Just because a stock is over-priced, doesn't mean the stock can't become more overpriced.
You can track these stocks at stockpickr.com.
Disclosure: Author does not own or short any of the above.