I have been buying Call options on individual stocks for approx 2 years and have been very successful. If I like a stock, instead of buying the stock I will buy CALLS on them. If the stock moves up as anticipated, I will sell the call to close out the position and take the profit. In most cases I sell (close out) my CALL that I purchased well before it expires. Recently I had 5 CALLS that were In The Money on a stock the Thursday before they expired. I planned to watch the stock on the next day (Friday) the day they expired to see if they would even go further in the money and then I was planning to sell (close out my position) by 4PM. But on Thursday I received email from my broker that I needed to notify them if I planned to close out my position by the next morning (Friday) due to "the event of an assignment or exercise on your expiring positions"......I had no idea what they meant but they said they might exercise or assign my in the money Call option the next day if I took no action.... So Friday morning, I sold my 5 Call options to close out my position instead of waiting till the end of the trading day on Friday...My question is I thought my buying CALLS gives me the RIGHT BUT NOT THE OBLIGATION to buy the underlying stock so why was the broker concerned about my CALL options?..And why couldn't I have waited until almost the end of the trading day Friday to sell (close out) my calls since the underlying stock did go higher during the day on Friday and I would have received even more money on the calls then I did?