Zacks Investment Ideas feature highlights four popular ETFs: IWM, TNA, SPY, and QQQ. These funds are widely followed by investors and offer exposure to different segments of the market. IWM tracks small-cap stocks, TNA provides leveraged exposure to small-cap stocks, SPY tracks the S&P 500 index, and QQQ focuses on technology stocks. Investors may consider these ETFs for their investment portfolios based on their specific investment objectives and risk tolerance.