What Is a Stock Split?

When Apple announced a 4-for-1 stock split in 2020, its stock jumped 10% in a single day. When Amazon announced a 20-for-1 split in 2022, shares surged 6%. This is strange, because stock splits change absolutely nothing about a company's value, earnings, or prospects. Understanding why splits happen — and why they shouldn't matter but sometimes do — reveals something important about investor psychology.

How It Works

A stock split increases the number of shares outstanding while proportionally reducing the price per share. In a 2-for-1 split, each share becomes two shares at half the price. A 4-for-1 split turns each share into four shares at one-quarter the price.

If you own 10 shares of a $1,000 stock and it does a 10-for-1 split, you now own 100 shares at $100 each. Your total investment is still exactly $1,000. Nothing about your ownership, the company's value, or your net worth has changed. It's like cutting a pizza into 8 slices instead of 4 — you have more pieces, but the same amount of pizza.

Reverse stock splits work in the opposite direction. A 1-for-10 reverse split turns 100 shares at $1 into 10 shares at $10. Companies do reverse splits to avoid being delisted from exchanges (which require minimum share prices) or to look more "respectable." Unlike regular splits, reverse splits are often a warning sign — the stock was so cheap that the company needed cosmetic surgery.

Companies split their stock when the share price gets high enough that it might deter smaller investors. Before Apple's 4-for-1 split in August 2020, a single share cost about $500. After the split, it cost about $125 — making it more accessible to retail investors. Berkshire Hathaway, famously, has never split its Class A shares, which trade at over $600,000 each. Warren Buffett believes that a high share price attracts long-term investors and discourages day traders.

The mechanics are handled automatically by your brokerage. You don't need to do anything — the new shares appear in your account on the split date.

Why It Matters for Investors

In theory, stock splits shouldn't affect returns at all. In practice, they often do — at least in the short term.

A study by David Ikenberry of Rice University found that stocks outperformed the market by an average of 8% in the 12 months following a split announcement. Why? Several theories:

Signaling. Companies typically split their stock when business is going well and the share price has risen significantly. A split signals management's confidence that the price will continue to rise.

Accessibility. Lower share prices make the stock available to more retail investors. While fractional shares have reduced this effect, many investors still prefer to buy whole shares.

Psychological anchoring. A $150 stock "feels" cheaper than a $600 stock, even though the underlying value is identical. This is irrational but real — behavioral finance repeatedly shows that nominal prices affect investor behavior.

Options liquidity. Stock options are priced per share, so a lower share price can make options trading more accessible and increase options volume, which can improve price discovery.

However, never buy a stock solely because it announced a split. The long-term performance of a company depends on its earnings, competitive position, and management — not the nominal share price. Stocks that split can still decline. Plenty of stocks that split in 2021 subsequently fell 50% or more in 2022.

Real Example

Here are some notable stock splits and what happened:

Apple — 4-for-1 split (August 2020): Share price was ~$500 pre-split, became ~$125. Over the next 12 months, shares rose about 30% to $153. Apple continued to execute flawlessly, so the gains were warranted — not caused by the split itself.

Amazon — 20-for-1 split (June 2022): Share price was ~$2,400 pre-split, became ~$120. Over the next 12 months, shares initially dropped to $85 during the 2022 bear market before recovering to about $130. The split didn't protect investors from broader market declines.

Tesla — 3-for-1 split (August 2022): Share price was ~$900 pre-split, became ~$300. Over the next 12 months, shares dropped to about $240. The split announcement created short-term excitement, but the stock's performance was ultimately driven by Tesla's business fundamentals and the broader market.

Citigroup — 1-for-10 reverse split (May 2011): This was done after the financial crisis destroyed Citi's stock price. Shares went from $4.50 to $45.00 post-split. The reverse split didn't fix Citigroup's problems — it was cosmetic surgery on a struggling company.