XLY tracks the Consumer Discretionary Select Sector Index, a roughly 50-stock slice limited to S&P 500 constituents. That narrow universe forces concentration. Amazon sits at 23.53% of the fund and Tesla at 18.97%, a combined 42.50% in two names, with the top three holdings totaling 50.44%. XLY bets that mega-cap discretionary leaders compound faster than the rest of the sector.
I watched it happen. On October 19, 1987, the Dow Jones Industrial Average tumbled 508 points, which was 22.6%. It fell from 2,246.74 at the open to 1,738.74 at the close on the day known as Black Monday. Such a drop would be just shy of 11,000 points today. The market was actually worse than that when taken over two days. The Dow had dropped almost 5% the Friday before. The anxiety over the weekend between the two was terrific.