looking at NVDA and its weightings in the SPY and the XLK (largest tech ETF)....
here are the weightings in each:
XLk SPY
AAPL. 21.8%. 7.1%
MSFT 22.7%. 6.7%
NVDA 5.0%. 3.0%
AVGO 4.34%. 0.95%
one can clearly see that the ratio of NVDA's weighting to those of AAPL, MSFT, AVGO differs completely between XLK and SPY... and I believe both of which purport to be market cap indices (not certain on XLK but I think so)......
this is a massive difference
I did learn recently that another big ETF, QQQ, is actually a capped-market cap weighted index.. I think AAPL is trimmed a little. not sure about MSFT.
and this is nitty (and not that important), but I see relative weights don't match up between AAPL and MSFT either. but it's pretty small difference (might just be how they deal with insiders shares)... I checked NVDA and it doesn't have significant insider shares.
thanks in advance