Two factors often determine stock prices in the long run: earnings and interest rates. Investors can't control the latter, but they can focus on a company's earnings results every quarter.Life and the stock market are both about expectations, and rising above what is expected is often rewarded, while falling short can come with negative consequences. Investors might want to try to capture stronger returns by finding positive earnings surprises.Hunting for 'earnings whispers' or companies poised to beat their quarterly earnings estimates is a somewhat common practice. But that doesn't make it easy. One way that has been proven to work is by using the Zacks Earnings ESP tool.The Zacks Earnings ESP, ExplainedThe Zacks Earnings ESP, or Expected Surprise Prediction, aims to find earnings surprises by focusing on the most recent analyst revisions. The basic premise is that if an analyst reevaluates their earnings estimate ahead of an earnings release, it means they likely have new information that could possibly be more accurate.Now that we understand the basic idea, let's look at how the Expected Surprise Prediction works. The ESP is calculated by comparing the Most Accurate Estimate to the Zacks Consensus Estimate, with the percentage difference between the two giving us the Zacks ESP figure.Bringing together a positive earnings ESP alongside a Zacks Rank #3 (Hold) or better has helped stocks report a positive earnings surprise 70% of the time. Furthermore, by using these parameters, investors have seen 28.3% annual returns on average, according to our 10 year backtest.Stocks with a ranking of #3 (Hold), or 60% of all stocks covered by the Zacks Rank, are expected to perform in-line with the broader market. Stocks with rankings of #2 (Buy) and #1 (Strong Buy), or the top 15% and top 5% of stocks, respectively, should outperform the market; Strong Buy stocks should outperform more than any other rank.Should You Consider BlackRock?The final step today is to look at a stock that meets our ESP qualifications. BlackRock (BLK) earns a #3 (Hold) 29 days from its next quarterly earnings release on October 12, 2021, and its Most Accurate Estimate comes in at $10 a share.By taking the percentage difference between the $10 Most Accurate Estimate and the $9.81 Zacks Consensus Estimate, BlackRock has an Earnings ESP of 1.89%. Investors should also know that BLK is just one of a large group of stocks with positive ESPs. All of these qualifying stocks can be filtered by ESP, Zacks Rank, % Surprise (Last Qtr.), and Reporting date.Don't forget to head to the Earnings ESP Home Page. There, you'll find lots more earnings-related investing strategies to help build a winning portfolio.Find Stocks to Buy or Sell Before They're ReportedUse the Zacks Earnings ESP Filter to turn up stocks with the highest probability of positively, or negatively, surprising to buy or sell before they're reported for profitable earnings season trading. Check it out here >> Tech IPOs With Massive Profit Potential: Last years top IPOs surged as much as 299% within the first two months. With record amounts of cash flooding into IPOs and a record-setting stock market, this year could be even more lucrative. See Zacks’ Hottest Tech IPOs Now >>Want the latest recommendations from Zacks Investment Research? Today, you can download 7 Best Stocks for the Next 30 Days. Click to get this free report BlackRock, Inc. (BLK): Free Stock Analysis Report To read this article on Zacks.com click here. Zacks Investment Research