How to Start Investing With $100
The most common reason people give for not investing is "I do not have enough money yet." This is the most expensive excuse in personal finance. Compound interest does not care how much you start with. It cares how long you have been investing.
The Compound Interest Miracle
$100 invested monthly at a 10% annual return (roughly the historical average of the S&P 500) for 40 years grows to approximately $637,000. The total amount invested is $48,000. The compound growth is $589,000 — more than twelve times the original investment. The person who waits ten years to start ends up with less than half that amount. Ten years of waiting costs over $400,000.
The Four Investment Vehicles Every Beginner Needs to Know
Index Funds. A collection of stocks that mirrors a market index — typically the S&P 500. When you invest in an S&P 500 index fund, you are buying a tiny piece of every major American company. Historical average annual return: approximately 10%. Extremely low fees, no active management required.
Roth IRA. A retirement account that allows you to invest after-tax dollars and withdraw them tax-free in retirement. The contribution limit in 2026 is $7,000 per year. If you do not have a Roth IRA, opening one should be your first financial priority after building a 3-month emergency fund.
Real Estate Investment Trusts (REITs). A company that owns income-producing real estate and is required to distribute at least 90% of its taxable income to shareholders. REITs allow you to invest in real estate with as little as $10, without the headaches of being a landlord.
High-Yield Savings Account. Before you invest in anything, you need an emergency fund — 3 to 6 months of living expenses in a liquid, accessible account. A high-yield savings account currently offers 4 to 5% annual interest.
The $100 Per Month Plan
Month 1–6: Open a high-yield savings account and direct your $100 there. Build your emergency fund to at least $1,000 before investing anything.
Month 7 onward: Open a Roth IRA at a low-cost brokerage (Fidelity, Vanguard, or Schwab). Invest your $100 per month in a target-date retirement fund or a low-cost S&P 500 index fund. Set up automatic contributions.
As your income grows: Increase your contribution by 1% of your income every time you get a raise. Most people never notice the difference in their take-home pay, but the compounding effect over decades is enormous.