How to Avoid a Lost Decade for Stocks

• As the Magnificent Seven giants keep gaining, concerns of stock-market concentration are rising. 
• A bursting of the AI bubble could see a lost decade for stocks similar to the end of the dot-com boom. 
• Diversifying portfolios is key for investors to avoid losses if the bubble deflates, Richard Bernstein told Business Insider. 

The artificial intelligence craze marches on, and with it, fears of growing co