Most of us don't even notice the few cents left over from a coffee or a grocery run, but that 'spare change' actually adds up to about $150 a month for the average person. In 2026, the smartest move you can make is automating the sweep of those tiny amounts into high-growth thematic ETFs. Whether you're passionate about renewable energy, cybersecurity, or the next generation of space tech, there are apps now that handle all the heavy lifting for you with almost zero fees. It might feel like literal pennies at first, but with the power of compound interest, you’re basically building a six-figure portfolio in the background of your life without even feeling the pinch. We’ve ranked the best micro-investing platforms to help you get started.