Investors might want to bet on Mercury General (NYSE: MCY), as it has been recently upgraded to a Zacks Rank #1 (Strong Buy). This rating change essentially reflects an upward trend in earnings estimates -- one of the most powerful forces impacting stock prices. The Zacks rating relies solely on a company's changing earnings picture. It tracks EPS estimates for the current and following years from the sell-side analysts covering the stock through a consensus measure -- the Zacks Consensus Estimate. The power of a changing earnings picture in determining near-term stock price movements makes the Zacks rating system highly useful for individual investors, since it can be difficult to make decisions based on rating upgrades by Wall Street analysts. These are mostly driven by subjective factors that are hard to see and measure in real time. As such, the Zacks rating upgrade for Mercury General is essentially a positive comment on its earnings outlook that could have a favorable impact on its stock price. Most Powerful Force Impacting Stock Prices The change in a company's future earnings potential, as reflected in earnings estimate revisions, has proven ...