1. Yardeni recommends market-weighting tech due to concentration risk in S&P 500. 2. He suggests overweighting financials, industrials, and healthcare sectors for better returns. 3. Concerns arise over competition amongst 'Magnificent 7' tech companies affecting profitability. 4. US MSCI index now makes up 65.1% of the All Country MSCI index. 5. A weaker dollar is favoring returns in foreign stock markets over the U.S.