When a company such as RBS splits its shares, the market capitalization before and after the split takes place remains stable, meaning the shareholder now owns more shares but each are valued at a lower price per share. Often, however, a lower priced stock on a per-share basis can attract a wider range of buyers. If that increased demand causes the share price to appreciate, then the total market capitalization rises post-split. This does not always happen, however, often depending on the underlying fundamentals of the business. When a company such as RBS conducts a reverse share split, it is usually because shares have fallen to a lower per-share pricepoint than the company would like. This can be important because, for example, certain types of mutual funds might have a limit governing which stocks they may buy, based upon per-share price. The $5 and $10 pricepoints tend to be important in this regard. Stock exchanges also tend to look at per-share price, setting a lower limit for listing eligibility. So when a company does a reverse split, it is looking mathematically at the market capitalization before and after the reverse split takes place, and concluding that if the market capitilization remains stable, the reduced share count should result in a higher price per share.

Looking at the RBS split history from start to finish, an original position size of 1000 shares would have turned into 51.25 today. Below, we examine the compound annual growth rate — CAGR for short — of an investment into RBS shares, starting with a $10,000 purchase of RBS, presented on a split-history-adjusted basis factoring in the complete RBS split history.