hi, when yesterday (Feb 20, 2018) NASDAQ 100 index was closed at 6,779.70, the QQQ was closed at 165.29. QQQ is supposed to be 1/40 of its index, but 165.29*40=6611.6, less than 168 points. Why such a large deviation? Thanks.
Hadn't paid attention to the discrepancy before and am not "looking into it" now... But with similar difference today, offer this as a possible explanation... The difference has existed for a long time, is continuing to grow, and may be the cumulative "costs" of the QQQ (since its inception) vs the index and has not been "reset" to be 1/40 of the index. (Not a difference you could arb nor anything of concern.) The QQQ is not the NDX per se, but rather a derivative product/security based upon the NDX. To manage the QQQ, there are costs... commissions, management fees, spreads, slippage, etc. If someone knows otherwise, perhaps they will chime in.
The QQQ closing prices of 165.29 was very accurate because this morning the ETF sponsor reported the closing Net Asset Value of 165.25, only 4 cents off the close. My _guess_ is that the QQQ and the NDX have slightly different component weightings. The ETF's components are updated every night by the sponsor, and published. I don't know when the index weightings are updated or published. I also don't know if the index reflects accumulated dividends; the ETF NAV does.