These surprising stocks could be some of the biggest drivers of S&P 500 earnings growth

Investors often focus on the largest companies by market capitalization when assessing S&P 500 earnings growth, but base effects can matter just as much. According to the report, Boeing, Meta and EchoStar recorded steep charges and expenses a year ago. Because those costs weighed heavily on prior-year results, this latest quarter's figures are expected to look especially strong by comparison—even if underlying business trends are unchanged.

This is a useful reminder of how year-over-year comparisons work. Earnings growth measures the change from the same period a year earlier, so an unusually weak base can mechanically inflate the current growth rate. A company that simply returns to more normal profitability after a one-time charge can appear to be expanding rapidly.

For market watchers, the key question is how much of the index's headline earnings growth reflects genuine operating improvement versus these low-base effects. It is worth monitoring company disclosures on the nature of prior charges and any guidance on whether similar costs could recur. Index-level earnings figures can also be skewed by a handful of large constituents, so the composition of growth deserves attention alongside the headline number.