Ecolab (ECL) could be a solid addition to your portfolio given its recent upgrade to a Zacks Rank #2 (Buy). This upgrade is essentially a reflection of an upward trend in earnings estimates -- one of the most powerful forces impacting stock prices.

A company's changing earnings picture is at the core of the Zacks rating. The system tracks the Zacks Consensus Estimate -- the consensus measure of EPS estimates from the sell-side analysts covering the stock -- for the current and following years.

Since a changing earnings picture is a powerful factor influencing near-term stock price movements, the Zacks rating system is very useful for individual investors. They may find it difficult to make decisions based on rating upgrades by Wall Street analysts, as these are mostly driven by subjective factors that are hard to see and measure in real time.

Therefore, the Zacks rating upgrade for Ecolab basically reflects positivity about its earnings outlook that could translate into buying pressure and an increase in its stock price.

Most Powerful Force Impacting Stock Prices

The change in a company's future earnings potential, as reflected in earnings estimate revisions, and the near-term price movement of its stock are proven to be strongly correlated. That's partly because of the influence of institutional investors that use earnings and earnings estimates for calculating the fair value of a company's shares. An increase or decrease in earnings estimates in their valuation models simply results in higher or lower fair value for a stock, and institutional investors typically buy or sell it. Their transaction of large amounts of shares then leads to price movement for the stock.

Fundamentally speaking, rising earnings estimates and the consequent rating upgrade for Ecolab imply an improvement in the company's underlying business. Investors should show their appreciation for this improving business trend by pushing the stock higher.

Harnessing the Power of Earnings Estimate Revisions

As empirical research shows a strong correlation between trends in earnings estimate revisions and near-term stock movements, tracking such revisions for making an investment decision could be truly rewarding. Here is where the tried-and-tested Zacks Rank stock-rating system plays an important role, as it effectively harnesses the power of earnings estimate revisions.

The Zacks Rank stock-rating system, which uses four factors related to earnings estimates to classify stocks into five groups, ranging from Zacks Rank #1 (Strong Buy) to Zacks Rank #5 (Strong Sell), has an impressive externally-audited track record, with Zacks Rank #1 stocks generating an average annual return of +25% since 1988. You can see the complete list of today's Zacks #1 Rank (Strong Buy) stocks here >>>>.