Intrepid Potash (IPI) could be a solid choice for investors given its recent upgrade to a Zacks Rank #2 (Buy). This upgrade primarily reflects an upward trend in earnings estimates, which is one of the most powerful forces impacting stock prices. Most Powerful Force Impacting Stock Prices 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 rat ...