This Top Growth Stock to Buy in March Fell 6% This Week, but Is Up More Than 200% in Just 3 Years

By Daniel Sparks – Mar 7, 2026 at 11:00PM ESTKey PointsInteractive Brokers has been an incredibly fast-growing asset-gathering machine, crossing 4.6 million client accounts in February.With an elite 79% pretax profit margin, the company turns incremental account growth into outsize bottom-line gains.The stock isn't cheap. But it's probably worth paying up for.Shares of Interactive Brokers (IBKR 2.00%) took a 6% hit this week. For recent buyers, the sudden drop might feel like whiplash. But zooming out tells a vastly different story. Long-term investors are sitting comfortably on massive gains. The electronic brokerage firm is up more than 200% over the last three years, easily crushing the broader market's returns. With this context, does a 6% pullback offer a rare entry point into a compounding machine, or is the stock finally running out of steam after a massive multi-year run? At a market capitalization of roughly $113 billion as of this writing and a price-to-earnings ratio of 30, expectations are high. But I think it can live up to those expectations over the long haul. Image source: Getty Images. A relentless asset-gathering machine Scanning the latest primary disclosures reveals a clear, decisive mechanism behind this stock's remarkable three-year run: Interactive Brokers is vacuuming up accounts at a blistering pace. In its February 2026 monthly metrics update, the company reported 4.646 million client accounts, representing a 31% year-over-year increase. This sustained pace builds on a record-breaking 2025, when the company added over 1 million net new accounts in a single year for the first time in its history. More importantly, total client equity in February -- the lifeblood of any brokerage -- jumped 40% year over year to hit $820 billion. This marks a notable acceleration from the 37% year-over-year growth rate the company posted at the end of 2025, when client equity sat at $780 billion. This is the decisive variable for investors. While trading volumes can fluctuate with market volatility, the steady accumulation of customer accounts and client equity provides a steady (and growing) foundation for future revenue. This influx of new money doesn't just sit idle. It directly feeds the company's highly automated brokerage, which leads to the second half of the bull case for the stock. An automated cost structure The defining trait of Interactive Brokers is its ruthless, technology-first, highly automated operating model with an emphasis on low costs -- and this is showing up in the company's bottom line. In Q4, the company posted an exceptional pre-tax profit margin of 79% -- up from 75% in the year-ago period. This operational leverage (the ability to grow revenue faster than operating costs) means that almost every new dollar of revenue flows directly to the bottom line. When customer equity grows, the costs to service that equity barely budge. How does this translate to the company's bottom line? Interactive Brokers reported fourth-quarter 2025 non-generally accepted accounting principles (non-GAAP) earnings per share of $0.65 per share -- up 27% year over year. This performance is "the direct result of our focus on empowering clients through low trade and margin pricing and less drag from costs," said Interactive Brokers managing director Nancy Stuebe during the company's fourth-quarter earnings call. Over time, this structural advantage attracts more professional and active traders, which leads to more trading and more commissions. In February, Interactive Brokers' Daily Average Revenue Trades (DARTs) climbed 21% year over year to 4.366 million. While impressive, this notably actually represents a deceleration from the 27% year-over-year volume growth the company saw in January, highlighting how trading activity can ebb even as assets grow. ExpandNASDAQ: IBKRInteractive Brokers GroupToday's Change(-2.00%) $-1.36Current Price$66.69Key Data PointsMarket Cap$30BDay's Range$65.27 - $67.4252wk Range$32.82 - $79.18Volume133KAvg Vol4.6MGross Margin95.08%Dividend Yield0.48% Why this is my top growth stock idea in March Of course, this is not a cheap stock at 30 times earnings. And after reviewing the company's underlying business momentum, you wouldn't expect it to be cheap. A valuation like this presents risks. If customer account growth decelerates materially, or if an unexpected shift in the interest rate environment severely compresses Interactive Brokers' net interest income, the stock's premium multiple will likely contract. In addition, given the stock's ties to the market and all the noise that comes with that, the stock will likely be volatile. But for investors willing to embrace the risks, look past any near-term noise and focus on the sheer volume of assets migrating to the platform, this week's roughly 6% pullback looks like a genuine opportunity to start a small position in the stock -- and possibly add to it on any bigger pullbacks. Overall, the company possesses a structural cost advantage that competitors cannot easily replicate, and it is aggressively turning that advantage into greater market share. Investors buying here are paying a premium, but they are paying for one of the highest-quality execution engines in the financial sector.Read NextMar 2, 2026 •By Eric VolkmanWhy Interactive Brokers Group Stock Was a Winner TodayDec 28, 2025 •By Marc GubertiInvesting in These 3 Millionaire-Maker Stocks Right Now Could Set You Up for LifeNov 22, 2025 •By Brett Schafer3 Brilliant Growth Stocks to Buy Now and Hold for the Long TermMay 19, 2025 •By Royston Yang3 Growth Stocks to Buy and Hold ForeverJul 27, 2023 •By Anthony Di PizioAre the Big Tech Stocks About to Take a Breather? Here's What This Broker ThinksMar 28, 2023 •By Anthony Di PizioHigher Interest Rates Make This Growth Stock a Big Winner -- and It's CheapAbout the AuthorDaniel Sparks is a contributing Motley Fool stock market analyst covering technology, industrials, financials, and consumer goods. Daniel is the owner and chief investment officer of Sparks Capital Management. He holds a master’s degree in business administration from Colorado State University. The Globe and Mail profiled him and his investing philosophy in an article titled, “This stock picker is outperforming nearly everybody else. Here’s how he is doing it.”TMFDanielSparksX@sparks_capitalStocks MentionedInteractive Brokers GroupNASDAQ: IBKR$66.69(-2.00%)-$1.36*Average returns of all recommendations since inception. Cost basis and return based on previous market day close.