The Earnings Announcement Premium

Every quarter, a public company releases its earnings on a known date, and the stock's realized volatility on that day is far higher than on an average trading day — the market is absorbing a genuine burst of new information all at once. What's less obvious is that simply holding a stock through its earnings announcement, on average and across many stocks, has historically earned a higher return than holding an equivalent stock on a random non-announcement day. That extra average return for bearing the announcement is the earnings announcement premium.

Why holding through the release pays

Ordinary daily stock volatility mostly reflects broad market risk, which diversifies away in a large portfolio. Earnings-day risk is different: it's firm-specific, concentrated into one day, and can't be hedged away by holding more stocks, because each holding has its own announcement date. Investors who are unwilling or unable to bear that concentrated risk — because they need predictable short-term returns, or because their mandate limits single-stock volatility — tend to sell out ahead of earnings and buy back after, transferring the risk (and, historically, a premium for bearing it) to those willing to hold through.

Worked example

Across a large sample of US stocks, one well-known study found that returns during the three-day window around earnings announcements averaged noticeably higher, on an annualized basis, than returns during non-announcement periods for the same stocks — even though announcement-day returns are far more volatile and can go sharply either way for any individual name.

Concretely: suppose a stock's average daily return outside earnings windows is 0.03%, but its average return on the three days bracketing an earnings release is 0.15% per day — five times higher. Over a year with four earnings releases (twelve announcement days total) versus roughly 240 non-announcement trading days, an investor who held only through the announcement windows would capture a disproportionate share of the stock's total annual return from just 5% of the trading days, at the cost of bearing outsized single-stock risk on each of those days.

What this means in practice

The premium is a compensation-for-risk story, not a free-lunch story — the same days that pay the premium on average are the days an individual stock can also gap down 15% on a bad print. Strategies built on this effect typically diversify across many upcoming earnings dates simultaneously, so that the concentrated single-name risk on any one report is small relative to the portfolio, while still capturing the aggregate premium across many announcements.