Each business day, TheStreet.com Ratings updates its ratings on the stocks it covers. The proprietary ratings model projects a stock's total return potential over a 12-month period, including both price appreciation and dividends. Buy, hold or sell ratings designate how the Ratings group expects these stocks to perform against a general benchmark of the equities market and interest rates.

While the ratings model is quantitative, it uses both subjective and objective elements. For instance, subjective elements include expected equities market returns, future interest rates, implied industry outlook and company earnings forecasts. Objective elements include volatility of past operating revenue, financial strength and company cash flows.

However, the rating does not incorporate all of the factors that can alter a stock's performance. For example, it doesn't always factor in recent corporate or industry events that could affect the stock price, nor does it include recent technology developments and competitive dynamics that may affect the company.

For those reasons, we believe a rating alone cannot tell the whole story, and that it should be part of an investor's overall research.

The following ratings changes were generated on April 8.

International Bancshares ( IBOC - Get Report), which provides commercial and retail banking services in Texas and Oklahoma, has been upgraded to buy. For the fourth quarter, net income increased 11% year over year to $35.4 million. Earnings per share rose to 52 cents from 45 cents in the same period, despite a 2.2% decrease in revenue to $205.4 million. The company's gross profit is rather high at 61%, and its net profit margin of 17% exceeds the industry average. Net operating cash flow has significantly increased to $32.5 million. International Bancshares had been rated hold since TheStreet.com Ratings initiated coverage on April 7, 2006.

NBTY Inc. which makes and sells nutritional supplements, has been upgraded to buy. For the first quarter, revenue increased 0.9% to $510.9 million, while earnings per share declined to 67 cents from 73 cents. The company's debt-to-equity ratio is very low at 0.19, implying very successful management of debt levels. In addition, NBTY has a quick ratio of 1.66, which demonstrates an ability to cover short-term liquidity needs. The gross profit is rather high at 56%, and the company's net profit margin of 9% is above the industry average.Return on equity has improved slightly from the year-ago quarter to 19%. This can be construed as a modest strength in the organization. The stock has a price-to-earnings ratio of 11.28, which makes it cheaper than others in its sector. NBTY had been rated hold since Jan. 22.

John Wiley & Sons ( JW.A - Get Report), which, together with its subsidiaries, publishes print and electronic products for professionals, consumers, researchers, students and educators, has been upgraded to buy. For the third quarter of 2007, revenue rose 45% year over year to $429.3 million, and earnings per share rose to 67 cents from 57 cents. Return on equity has improved slightly to 21%, which is well ahead of the industry average. Net operating cash flow has increased 81% to $301.8 million from the year-ago quarter. The stock has risen at a faster pace than the S&P 500 in the past year. We see additional upside potential in the coming year. John Wiley & Sons had been rated hold since July 31.

S&T Bancorp ( STBA - Get Report), the holding company for S&T Bank, has been upgraded to buy. For the fourth quarter, revenue increased 0.7% year over year to $62.9 million, and earnings per share climbed to 54 cents from 52 cents. For 2008, the market expects an improvement in full-year EPS to $2.36 from $2.25 in 2007. Return on equity has improved slightly to 17% from the year-ago quarter, exceeding the industry average. The company's gross profit margin is rather high at 61%, and its net profit margin of 21% beats the industry average.Net operating cash flow has significantly increased to $15.9 million. S&T Bancorp had been rated hold since Jan. 9.

Tyco ( TYC), which provides to customers worldwide various products ranging from electronic security and alarm monitoring to water purification and flow control solutions to galvanized steel tubes and armored wire and cable, has been upgraded to hold. Strengths such as revenue growth, a solid financial position and improvement in earnings per share are countered by deteriorating net income, disappointing return on equity and weak operating cash flow. For the first quarter, revenue improved 12% year over year to $4.87 billion, and earnings per share grew to 74 cents from 32 cents. The company's debt-to-equity ratio is very low at 0.28, but its quick ratio of 0.80 is somewhat weak and could be cause for future problems. Return on equity has greatly decreased from the year-ago quarter and significantly trails the industry average. This is a signal of major weakness within the corporation. Tyco had been rated sell since Nov. 21.

Additional ratings changes from April 8 are listed below.

Ticker Company Name Change New Rating Former Rating
GBCI GLACIER BANCORP INC Upgrade Buy Hold
IBOC INTL BANCSHARES CORP Upgrade Buy Hold
NTY NBTY INC Upgrade Buy Hold
STBA S & T BANCORP INC Upgrade Buy Hold
TYC TYCO INTERNATIONAL LTD Upgrade Hold Sell
UNAM UNICO AMERICAN CORP Downgrade Hold Buy
JW.B WILEY (JOHN) & SONS Upgrade Buy Hold
JW.A WILEY (JOHN) & SONS Upgrade Buy Hold
WLFC WILLIS LEASE FINANCE CORP Upgrade Buy Hold
WRLD WORLD ACCEPTANCE CORP/DE Upgrade Buy Hold
MWIV MWI VETERINARY SUPPLY Upgrade Buy Hold
CLMT CALUMET SPECIALTY PRODUCTS Downgrade Sell Hold
NECB NORTHEAST COMMUNITY BANCORP Upgrade Hold Sell
EBS EMERGENT BIOSOLUTIONS INC Upgrade Hold Sell
DCT DCT INDUSTRIAL TRUST INC Upgrade Hold Sell

This article was written by a staff member of TheStreet.com Ratings.