I don't understand this example of Pin risk (options) - Wikipedia.
When the call buyer exercised, wouldn't $\color{limegreen}{\text{exercise}}$ have automatically and instantly bought him 1000 shares @ $90?
How does the call buyer have "thirty seconds before the close" to $\color{red}{\text{buy back}}$ IBM shares @ \$89.95?
For example, a trader is long 10 calls struck at \$90 on IBM stock, and five minutes before the close of trading, IBM's stock price is \$89.75. These calls are out of the money and therefore will expire worthless at this price. However, two minutes before the close of trading, IBM's price suddenly moves to \$90.26. These options are now in the money, and $\color{limegreen}{\text{the trader will now want to exercise them}}$. However, to do so, the trader should first sell 1000 shares of IBM at \$90.26. This is done so that the trader will be flat IBM stock after expiration. Thirty seconds before the close, IBM drops back to \$89.95. The calls are now out of the money, and the trader must quickly $\color{red}{\text{buy back the stock}}$. Option traders with a broad portfolio of options can be very busy on Expiration Friday.