The S&P 500 managed a slight gain in September, finishing up less than 1%. Going into October, attention is shifting to Q3 earnings. Alphabet, Amazon, and Microsoft are reporting in the second half of the month. The main thing to watch is their 2027 capital expenditure guidance for AI data centers. The market expects them to increase spending, but the exact amount is the big question. If these companies can justify the higher budgets with strong cloud revenue growth, it should be positive for their stocks and related chipmakers like Nvidia, TSMC, and Broadcom. Since these megacaps make up over a third of the S&P 500, their results will largely set the direction for the broader market.