BOSTON (TheStreet) -- The stock-market crash that started almost two years ago pushed hundreds of companies' shares close to zero. Many are still trading at less than $5, stoking investor fears that bankruptcy is imminent.

There are few reliable gauges to determine which companies are at a higher risk of going broke than others. The Altman Z-score is one of them.

The Altman Z-score, a formula developed by New York University professor Edward Altman in 1968, measures companies' financial health to predict which may enter bankruptcy within two years. The gauge was 80% to 90% accurate on samples of distressed firms one year prior to bankruptcy by examining working capital, retained earnings and other measures, according to Altman's study.

Altman Z-scores carry three classifications. Companies with an Altman Z-score of at least 3 are considered "safe," while those with 1.8 or less are "distressed." Those in between are in a gray zone. Some stocks trading under $5 even have a negative score.

TheStreet ranked companies on the New York Stock Exchange and Nasdaq trading at less than $5 with a minimum $5 million market value and the strongest Altman Z-score. Each company's current ratio is given, which helps measure the ability to meet short-term obligations.

5. Nymox Pharmaceuticals ( NYMX - Get Report) in July said the Safety Monitoring Committee meeting for the Phase 3 U.S. pivotal trials of its benign prostatic hyperplasia (BPH) drug NX-1207 was "favorable and indicated no significant safety concerns for the trials to date. NX-1207 has been shown to improve the signs and symptoms of BPH, producing improvements which reached statistical significance compared to double-blinded placebo and study controls," the company said.

Altman Z-score: -65.69

Closing Price: $4.43 (Aug. 4)

2010 Total Return: -2.9%

Current Ratio: 0.83. A current ratio below 1 indicates that Nymox would have difficulty meeting its short-term obligations with current assets if those liabilities came due.

Consensus: EVA Dimensions had a "hold" rating on the stock as of July 2. No other firm covers Nymox shares.

4. Wave Systems ( WAVX) is a hardware-based digital-security company whose stock has languished below $5 because it's issued so many shares. In the first few months of 2009, Wave Systems launched four stock offerings totaling nearly $6.3 million to fund research and development of its security technology. Wave Systems CEO Steven Sprague told TheStreet in March that the company raised capital aggressively in the past, and that Wave is primed to benefit from the shift to emerging markets of hardware-based digital security.

Altman Z-score: -72.49

Closing Price: $3.23 (Aug. 4)

2010 Total Return: 127.5%

Current Ratio: 1.21, an indication that Wave Systems would be able to pay off current liabilities if they came due using current assets.

Consensus: Two research firms cover Wave Systems, with one recommending investors buy the stock and the other with a "hold" rating. MDB Capital has the lone "buy" rating and a $6 price target, noting that Wave Systems should benefit as companies are searching for better ways to protect data due to escalating consumer and legal costs associated with breaches.

3. Wizzard Software ( WZE) is a computer-software and media-services company. In June, Wizzard announced that Google ( GOOG) has begun including Apple's ( AAPL) iTunes "Buy Now" pages for the company's 300 iPhone Apps in its search results on mobile devices. As a result, Wizzard says it expects consumption of the company's podcast content to increase significantly. Even so, more than half of Wizzard's revenue stems from services to the health-care industry.

Altman Z-score: -80.75

Closing Price: 18.2 cents (Aug. 4)

2010 Total Return: -46.5%

Current Ratio: 1.17, which shows that Wizzard would be able to use its current assets to pay back its short-term liabilities if they came due.

Consensus: No research firm has coverage on Wizzard shares.

2. Asure Software ( ASUR - Get Report) is a workforce-management software company, previously known as Forgent Networks until the 2007 acquisition of iEmployee. The company has been in frequent patent disputes, including a 2007 case against Echostar ( SATS) in which a jury found that Forgent's patent was invalid. Before a 1-for-10 reverse stock split in December 2009, Asure shares traded as low as 25 cents.

Altman Z-score: -97.19

Closing Price: $2.20 (Aug. 4)

2010 Total Return: -24.1%

Current Ratio: 1.03, which indicates Asure would be able to pay off its short-term obligations should they come due now.

Consensus: Asure Software is not followed by any research firm.

1. Repros Therapeutics ( RPRX) has been on the Nasdaq's chopping block due to a failure to meet the exchange's minimum-bid-price requirement, although the company has said "a positive FDA response for its Androxal hypogonadism program will result in an increase in the market cap of the company and hence its share price." In July, Repros said it began a low-dose study of the safety and efficacy of Proellex to treat patients with reproductive disorders. On Tuesday, Repros halted its at-the-market program due to limitations from the Securities and Exchange Commission, having raised $6.8 million of the $7.8 million it expected.

Altman Z-score: -145.84

Closing Price: 37.1 cents (Aug. 4)

2010 Total Return: -53.4%

Current Ratio: 0.63, indicating that Repros would be unable to meet its short-term liabilities with its current assets.

Consensus: Repros Therapeutics isn't rated by any stock analyst.

-- Written by Robert Holmes in Boston.

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Disclosure: TheStreet's editorial policy prohibits staff editors, reporters and analysts from holding positions in any individual stocks.