These are mostly driven by subjective factors that are hard to see and measure in real time.As such, the Zacks rating upgrade for Kyndryl Holdings, Inc. is essentially a positive comment on its earnings outlook that could have a favorable impact on its stock price.Most Powerful Force Impacting Stock PricesThe 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.