EMH: Expectations and Share Price
In an efficient market, a share price already reflects what investors expect to happen. So the price moves on surprises, not on news itself. A company can report record profits and still see its stock fall if those profits came in below what the market expected.
What you will learn
- Why share prices reflect expected results, not past results
- What priced in means
- Why a stock can fall on good news and rise on bad news
- How an earnings surprise moves the price
- How this connects to the efficient market hypothesis
The formula
- EPS
- earnings per share
- Expected EPS
- the market's (consensus) forecast before the announcement
Worked example
The market expects EPS of $2.00 and prices the stock at 15 times expected EPS. The company reports EPS of $1.90, up from $1.50 last year. Assume the market now expects $1.90 and keeps the same multiple. What happens to the price?
- Price before the announcement = 15 × $2.00 = $30.00
- Earnings growth vs. last year = $1.90 ÷ $1.50 − 1 ≈ 27%
- Surprise = $1.90 − $2.00 = −$0.10, a miss
- New price = 15 × $1.90 = $28.50, a fall of 5%
Answer: Even with earnings up about 27%, the stock drops about 5% to $28.50, because results missed what was already priced in.
Common questions
Why do stocks fall after good earnings?
Because the share price already reflected high expectations before the announcement. If results, guidance or margins come in below what investors expected, the price falls to match the lower outlook, even if profits grew strongly compared with last year.
What does priced in mean?
Priced in means the market has already factored a piece of information or an expected event into the current share price. When that event actually happens as expected, the price may barely move, because nothing new has been learned.
What is an earnings surprise?
An earnings surprise is the difference between a company's reported earnings and what analysts or the market expected. A positive surprise often lifts the stock price, and a negative surprise often lowers it, regardless of whether earnings rose or fell year on year.
How do expectations relate to the efficient market hypothesis?
If markets are efficient, prices already include everything investors can reasonably expect. Only new, unexpected information should move the price. That is why share prices react to surprises rather than to news that was widely anticipated.