Dividing each share into several new shares – the price falls accordingly and total value stays the same.
In a 4-for-1 split, each shareholder receives four new shares for every old one and the price drops to a quarter. Nothing changes about the value of the company or of your holding. Companies usually split after a big price rise, to make shares easier for small investors to buy. A reverse split does the opposite, often for companies whose shares have fallen to pennies.