$iShares Top 20 U.S. Stocks ETF (TOPT.US)$ why cannot buy overnight

Brief summary of this post;
1. Follow @Ultratech he’s great if you haven't already
2. Leveraged ETF on $S&P 500 Index (.SPX.US)$
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So we (with an Ultraman guy) are chatting about the new ETF by BlackRock, $iShares Nasdaq Top 30 Stocks ETF (QTOP.US)$ which comprises of 30 stocks from Nasdaq.
He also shared another new ETF, which is $iShares Top 20 U.S. Stocks ETF (TOPT.US)$ with huge upward potential.
Then the conversatio...