The Share Count Question: How Many Shares Should I Buy?

Before you click that “BUY” button, there’s a critical question hiding beneath the surface—one that most beginner investors never ask. It’s not the obvious one about which stock to buy. It’s the one about position sizing. The answer determines whether your winning trades multiply your wealth or your losing trades obliterate it. Let me walk you through how I think about it, using a real example that stumbled across my desk recently.

When Position Size Becomes Your Silent Partner

L&L Energy made headlines when a former U.S. Secretary of Transportation and Commerce joined its board. The announcement caught my attention enough to dig deeper, and what I found was compelling: a Chinese coal company acquiring existing mines at a fraction of the cost of developing new ones. With the Chinese government shutting down mines producing less than 300,000 tons annually, L&L had positioned itself perfectly to roll up these operations. The company had already snagged three operating mines, two coal-washing facilities, a coking facility, and a distribution network. With triple-digit revenue and earnings growth across three consecutive quarters and a price-to-earnings ratio of just 9, here was a textbook opportunity.

But here’s the thing—identifying the opportunity is only half the battle. The other half is deciding how much of your capital goes into it. And that’s where everything hinges on a single decision: how aggressive do you want to be?

The Aggressive Growth Investor’s Dilemma

Let’s say you’ve decided you’re a growth investor rather than a value investor. (Value investors spread their capital across dozens of holdings to minimize risk. Growth investors? We’re playing a different game.) As a growth investor, you face a spectrum of aggressiveness. At one extreme, you could take your entire allocation and dump it into a single stock. A 10% appreciation of that one holding shoots your portfolio up 10%. The downside? A 10% decline cuts just as deep.

The Cabot Market Letter maintains what I’d call a moderately aggressive stance with 12 holdings in their portfolio. That’s diversified enough to weather a blow but concentrated enough to benefit from your best ideas. Cabot’s China & Emerging Markets Report runs even hotter with just 10 stocks—a truly aggressive posture. With that approach, a 10% gain in one holding lifts your entire portfolio by exactly 1%.

Here’s the framework I use: if you want to be an aggressive growth player, mentally divide your growth capital into ten equal buckets. Each bucket is your full position size for any new purchase. Your stock’s current price then determines the actual share count. If you’re allocating $10,000 to aggressive growth, each position starts with a $1,000 budget. A stock trading at $10 gets you 100 shares. Intuitive Surgical trading at $327? You’re taking three shares—not 100, not 50, but three.

The old Wall Street rule about 100 shares being a “round lot” comes from ancient history, when human brokers got price breaks for round-number purchases and passed savings to clients. Modern electronic brokers don’t care. Ten shares, one share, or 847 shares—they charge you the same way. This is your tactical advantage: indifference to share count liberates your position-sizing strategy.

History’s Hidden Lesson About Concentration Risk

Here’s something most investors don’t realize: history has a lot to teach about what happens when you’re too concentrated in a single strategy or geography. Consider Zheng He, the Muslim admiral who commanded China’s greatest naval expeditions in the early 15th century. Starting in 1404, Zheng He led seven voyages with fleets vastly superior to anything Europe could field—ships with nine masts stretching 416 feet carrying 28,000 men across 317 vessels.

These fleets explored the Indian Ocean, reached Africa, visited Hormuz and the Persian Gulf, returned with giraffes and envoys from 30 states, suppressed pirates, established trading colonies, and mapped coastlines from China to Africa. It was, by any measure, a triumph of exploration, commerce, and military power. Zheng He’s ships rotted in port after his death in 1433.

Why? Because China made the opposite of your position-sizing decision. The new emperor shifted focus northward to defend against Mongol threats. Confucian scholars, competing with court eunuchs for influence, convinced the government that international trade was weakness. China banned ocean-going ship construction. Building a multi-masted vessel became a capital offense. The same energy and intellect that built those fleets got redirected to the Forbidden City and the Great Wall.

The lesson isn’t historical trivia—it’s a market principle. China bet everything on one strategic posture: isolation. They concentrated entirely on inward defense. For centuries, this crushed their development. They missed the Pacific opportunity entirely. By the time the West arrived from the east, China was vulnerable and fractured. A different allocation strategy—maintaining even modest maritime capability—might have changed everything.

The Market Tests You Like History Did

Your portfolio isn’t different from China’s position problem, just compressed into years instead of centuries. The market tests you on multiple fronts simultaneously. In downtrends, the danger is holding losers too long—giving them too much portfolio weight. In bull markets, the risk is staying underinvested in your leading positions. You need to size your positions smartly enough to both survive the downtrends and capitalize on the uptrends.

That’s why the share count question matters. It’s not just arithmetic. It’s the difference between a position that lets you sleep at night and one that wakes you at 3 a.m. in a cold sweat. Divide your allocation into ten equal buckets. Let the stock price determine the share count. Don’t fool yourself with outdated ideas about what a “full position” should look like. The market will test you on whether you’ve thought through this clearly. Make sure your answer is ready before that test comes.