Apple, Microsoft become S&P 500's biggest duo in decades

Apple Inc. and Microsoft Corp. play a bigger role in the S&P 500 Index these days than any two companies have in decades. The maker of iPhones and the supplier of Windows software accounted for 12.5% of the index’s value between them as of Tuesday. Their combined weight exceeded every year-end total for the S&P 500’s top two companies since 1980, according to data compiled by Bloomberg and S&P Dow Jones Indices LLC. International Business Machines Corp. and American Telephone & Telegraph Co. together were 10.9% of the index in 1982, before AT&T was broken up.

 

Five biggest companies in the S&P 500

There’s a distinction to be made between the S&P 500 Index’s five biggest companies and all the rest, according to BCA Research. The firm compared the total market value of the five -- Amazon.com Inc., Apple Inc., Facebook Inc., Google owner Alphabet Inc. and Microsoft Corp. -- with the value of the other 495 companies in a chart last week. The top five’s value increased 266% from the start of 2015 through Tuesday, according to data compiled by Bloomberg. In the same period, the value of the rest rose just 25% -- and the entire gain occurred after the S&P 500 set this year’s low in March.

Apple, Microsoft pack S&P 500's biggest punch in decades

Apple Inc. and Microsoft Corp. have more power to set the S&P 500 Index’s course than any two companies have had in decades. Their combined weight closed at more than 10% on Monday for the first time ever, according to data compiled by Bloomberg. The total exceeded a December 1999 peak of 9.4% for Microsoft and General Electric Co., which had the most weight back then. The S&P 500’s top-two weights since the mid-1980s were cited in a Twitter post Monday by Carter Worth, head of technical analysis at Cornerstone Macro LLC.