BOSTON (TheStreet) -- Companies that trade for less than $5 a share typically are viewed as speculative and at risk of going broke. That's not always the case. Fortunately for investors, there is a reliable measure to help predict a company's bankruptcy risk.

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

, NYSE Amex and

Nasdaq

trading at less than $5 with a minimum $5 million market value and the highest Altman Z-score. Each company's quick ratio is given, helping to measure the ability to meet short-term obligations.

5.

American DG Energy

(ADGE)

Company Profile

: American DG Energy distributes, owns and operates clean, on-site energy systems that produce electricity, hot water, heat and cooling.

Altman Z-score

: 54.8

Closing Price

: $3.15 (Sept. 15)

Financial Metrics

: American DG Energy has a price-to-book ratio of 11.8, which suggests the stock may be overvalued based on book value. American DG Energy's quick ratio, which measures the ability to meet short-term obligations with its most liquid assets, is 1.4, indicating the energy-systems company should be able to meet its current liabilities.

Analyst Consensus

: There are currently no research firms with coverage of American DG Energy.

4.

BioTime

(BTIM)

Company Profile

: BioTime is engaged in the business of developing blood plasma volume expanders and related products and stem-cell-related products, and technology for diagnostic, therapeutic and research use.

Altman Z-score

: 55.66

Closing Price

: $4.65 (Sept. 15)

Financial Metrics

: BioTime has a price-to-book ratio of 7.22, which suggests the stock may be overvalued based on book value. BioTime's quick ratio, which measures the ability to meet short-term obligations with its most liquid assets, is a whopping 13, indicating the company would have no trouble meeting its current liabilities.

Analyst Consensus

: No analyst has coverage on BioTime.

3.

Uranerz Energy

(URZ)

Company Profile

: Uranerz Energy is an exploration-stage company engaged in the acquisition, exploration and development of properties in the uranium industry.

Altman Z-score

: 66.26

Closing Price

: $1.31 (Sept. 15)

Financial Metrics

: Uranerz Energy has a price-to-book ratio of 3.33, which suggests the stock may be slightly overvalued based on book value. Uranerz's quick ratio, which measures the ability to meet short-term obligations with its most liquid assets, is 27, a sign the uranium company should easily be able to meet its current liabilities.

Analyst Consensus

: Two analysts cover Uranerz Energy and both recommend that investors buy shares. That's down from three "buy" ratings a month ago.

2.

Rexahn Pharmaceuticals

(RNN)

Company Profile

: Rexahn Pharmaceuticals is a clinical-stage biopharmaceutical company developing and seeking to deliver novel cures for cancer and disorders of the central nervous system to patients worldwide.

Altman Z-score

: 69

Closing Price

: $1.24 (Sept. 15)

Financial Metrics

: Rexahn Pharmaceuticals has a price-to-book ratio of 6.25, which suggests the stock may be overvalued based on book value. Rexahn's quick ratio, which measures the ability to meet short-term obligations with its most liquid assets, is 11, indicating the biopharmaceutical company would be able to meet its current liabilities.

Analyst Consensus

: No research firm has coverage on Rexahn, although one had a "buy" rating on the stock about three months ago.

1.

Pure Bioscience

(PURE)

Company Profile

: Pure Bioscience develops bioscience products, including antimicrobials.

Altman Z-score

: 69.8

Closing Price

: $2.05 (Sept. 15)

Financial Metrics

: Pure Bioscience has a price-to-book ratio of 11.9, which suggests the stock may be overvalued based on book value. Pure's quick ratio, which measures the ability to meet short-term obligations with its most liquid assets, is 4.9, indicating the company should be able to meet its current liabilities.

Analyst Consensus

: Only one firm follows Pure Bioscience, recommending that investors buy shares of the bioscience products maker

-- Written by Robert Holmes in Boston

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