Costco's stock, trading under the symbol $COST, has reached a new all-time high, surpassing the $900 mark for the first time. This milestone comes as the company has more than doubled the performance of the S&P 500 over the past five years, and its stock is up 40% year-to-date. Investors have shown strong interest, with notable activity in call options for October and December, indicating expectations of further price increases. The stock's valuation is high, with a forward price-to-earnings ratio exceeding 50, comparable to some AI stocks.