I'm curious about some of the arithmetic in the market.

Google (Alphabet) has two classes in the S&P 500 (GOOG class C and GOOGL class A). Morningstar shows each of the two classes are capitalization 1.5 Trillion, which I add to $3 Trillion. This sum (today) is very slightly greater than Apple APPL (2.99T). Yet Apple gets all the news about being the first to reach $3T, and Alphahbet is not mentioned in that regard.

The S&P 500 weighting (according to https://www.slickcharts.com/sp500) weights each Google class at 1.947 and 1.687 which I add to 3.63% effect, but Apple weights at 7.61% (even though Alphabet capitalization sum seems slightly higher, and certainly not near half which seems clearly wrong mathematically).

What do I not understand? I do know two classes in the S&P 500 is prohibited, but grandfathered in this case. The only explanation I can imagine is if the Google capitalization sum is only $1.5T but which Morningstar still shows for both classes. If so, wouldn't that be technically incorrect? At least confusing.

  • 2
    It's not 1.5T each, it's 1.5T total
    – littleadv
    Commented Jul 6, 2023 at 16:27

1 Answer 1


The market cap reported is the total market cap of all classes of shares that have ownership rights, so it's incorrect to add the reported market cap of each class. So it's the "size" of the company, not just the size of that class of shares.

I can't think of a valid reason to report the "market cap" of an individual class of shares, since each class represents ownership in the same company, just with different voting rights.

I suppose if one investor wanted to own a majority (plus whatever amount is needed to overcome the private class B shares) of the class A shares to "control the company" they would need to know how much to buy, but that could easily be computed by anyone it applied to. In general, it is more informative to report the size of the company rather than just the size of that class of shares.

  • Thanks both. That's all I could imagine, but it seemed to say different. I was hung up thinking capitalization was stock shares x price, and the price of the two classes is slightly different, so I assumed the classes had to be individual.
    – WayneF
    Commented Jul 6, 2023 at 16:42

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