Ellington Credit (NYSE: EARN) could be a solid addition to your portfolio given its recent upgrade 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 sole determinant of the Zacks rating is a company's changing earnings picture. The Zacks Consensus Estimate -- the consensus of EPS estimates from the sell-side analysts covering the stock -- for the current and following years is tracked by the system. 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. Therefore, the Zacks rating upgrade for Ellington Credit 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, ...