TM Editors' note: This article discusses a penny stock and/or microcap. Such stocks are easily manipulated; do your own careful due diligence.

During the last six months, the stock market has taken a tumble, with the S&P 500 down almost 20% year-to-date. Some investors and traders are now looking for bargains, hoping for a short-term or even a long-term bounce.

So, how do you go about choosing a stock to buy in these volatile times? One strategy is to look for stocks that are not only selling below their book value, but also below their cash per share, especially if the company has low or no debt.

The cash per share is the amount of money that would be distributed for each share if the company went out of business today. In other words, if all the other company’s assets were totally worthless, how much would shareholders receive for each share, just from the cash in the bank the company has.

So if you can buy the stock for less than the cash per share, you should be getting a fairly good deal, not counting other factors. If the company is also profitable, that is another benefit.

The following are four stocks with have low or no debt, have recently been trading below the cash per share, and are profitable with price to earnings ratios below 32. As a matter of fact, three of the companies have P/E ratios below 15. All of the following are low-cap or extremely low-cap, so they should be considered very, very speculative.

Atea Pharmaceuticals, Inc. (AVIR), with a market cap of approximately $607.78 million, is a biopharmaceutical company, which is involved in the development of antiviral therapeutics for patients suffering from viral infections. The stock has a reasonable P/E of 14.02, debt amounting to 2.88 million, and has recently been selling for 17% below its cash per share.

Rubicon Technology, Inc. (RBCN) is an Illinois-based company, involved in the production of monocrystalline sapphire for applications in optical and industrial systems. It has a market cap of around $22.26 million. The P/E ratio is 30.63 and the company has no debt. It has been selling for 15% below cash.

Sesen Bio, Inc. (SESN), based in Cambridge, Massachusetts, develops targeted fusion protein therapeutics for the treatment of patients with cancer. The market cap is around $159.35 million and the P/E is 3.23. The company only has $100,000 in debt. The stock has recently been selling at 4% below cash.

SunLink Health Systems, Inc. (SSY) is a provider of healthcare products and services, and is based in Atlanta, Georgia. It has an extremely low, and therefore extremely speculative, market cap of only $6.9 million. The P/E is 1.47 and the amount of debt is $1.31 million. The stock has recently been selling for 1% below cash.

As previously mentioned, all these stocks should be considered extremely speculative. Remember, stocks often sell for a very low price for a reason.