Stock split

In a stock split a company increases the number of shares in issue and reduces the price by the same factor, so a holder of one hundred shares at two hundred euros ends up with four hundred shares at fifty. The total value is unchanged and no money moves. A reverse split runs the other way, replacing many cheap shares with fewer expensive ones.

Why it matters

Nothing about your ownership changes, which is exactly why splits are dangerous for records. Every figure that depends on a share count has to be adjusted at once: the cost basis per share, the dividend per share, the historical price series and any spreadsheet formula built on them. Miss one and the position quietly reports a wrong average price for the rest of its life, and every gain and yield derived from it inherits the error. Historical prices published today are usually already adjusted, while your own old purchase rows are not.

How BullBenchmark shows it

We rebuild each position from the transaction rows in your file, so the share count and average cost shown are the ones your export supports. If a split reached your broker but not your file, the position count will not match the app you can check it against, and clicking the position opens the transactions behind it so you can see which rows are responsible. That drill-down is available on the demo portfolio.

Related terms

Corporate action · Cost basis · ISIN

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