The earnings game on Wall Street is stacked in favor of generating positive headlines for companies as they “beat” earnings estimates. Investors have learned to take many earnings-season “surprises” with a grain of salt, but some surprises are important enough to drive analysts’ estimates significantly higher, which in turn can support higher share prices over the long term.

Before showing you which large-cap companies have shown the largest revenue surprises this earnings season, it helps to understand how common certain surprises can be.

For starters, “earnings season” isn’t a cut-and-dry period, because many companies have fiscal quarters that end in the middle of the calendar quarter. For the S&P 500 SPX, +0.93% through May 15, FactSet had data for 454 companies for fiscal quarters ended Feb. 17 or later. So the following lists are derived from 91% of the components of the large-cap benchmark index.

The Wall Street earnings game is played by the companies, who might understandably underpromise and then overdeliver with earnings-per-share numbers, as well as the sell-side analysts who base their estimates in part on the “guidance” provided by the companies. Through May 15, 83% of S&P 500 companies that had reported so far this earnings season had beaten consensus earnings-per-share estimates, according to S&P Global Market Intelligence.

Keep in mind that beating an estimate may set up a good headline even if the overall story is negative. Maybe a company beat an estimate because its decline in earnings or sales was less than expected. Going further, maybe even a decline in sales has a silver lining if profit margins rise.

So the 83% earnings “beat rate” isn’t a surprise. But 43% of the companies beat their sales (or revenue) estimates. The sales numbers might be of greater interest, in part because of all the one-time events that can skew earnings figures.

Positive sales surprises

Among the 454 S&P 500 companies for which FactSet had data for fiscal quarters ended Feb. 17 or later, these are the 10 companies that have had the highest positive revenue surprises through May 15. Sales estimates before the earnings report reflect the consensus of analysts.

If you are a shareholder or considering an investment in any of these companies, you should do your own research to understand why sales rose for the quarter. Sometimes one-time factors are at play.

Fifth Third Bancorp FITB, +1.02% of Cincinnati is an interesting example. The company sold shares of WorldPay WP, +1.11% the payment processor formerly known as Vantiv, in the first quarter. Bank financial statements include gains on a sale as noninterest income, which is actually a revenue figure.

Keeping in mind that a positive surprise for sales (or earnings for that matter) may not signal an overall trend, here are comparisons of the quarterly sales numbers to those from a year earlier, along with gross profit margins:

A company’s gross margin is its sales less the cost of goods sold, then divided by sales. It doesn’t reflect overhead expenses, but it does give an indication of a company’s pricing power. A widening margin while sales are increasing is a good sign. A narrowing margin might mean a company is juicing sales or being forced to defend its market share by offering discounts on its products or services. Gross profit margins aren’t available for banks and insurance companies.

A company with a sales surprise may have actually seen a decline in revenue — HollyFrontier HFC, +2.06% is an example. The refiner also showed a significantly improved gross margin.