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LearnPaper Trading Lab › Module 3

Module 3 · Building a Starter Portfolio With $100,000 Core

Most practice accounts end up as a pile of tickers someone happened to like on the day they opened it. That teaches nothing, because there is no plan to test. This module builds a portfolio the other way round: plan first, structure second, sizes third, and only then the tickers.

~13 min read · Not started

By the end of this module you'll be able to

  • Write a five-line investment plan before placing a single trade.
  • Structure a portfolio as a diversified core plus smaller satellite positions.
  • Size each individual stock from a risk budget and turn the dollar amount into a share count.
  • Decide how much cash to hold, and handle the simulator’s missing currency conversion.

The plan comes first

A plan does not need to be long. It needs to exist before the first trade, because a plan written afterwards is just a description of what you already did. Five lines are enough:

A five-line plan1. Goal: what this money is for (a practice run for retirement investing, say). 2. Horizon: how long before you would need it. 3. Mix: the rough share in broad funds, individual stocks and cash. 4. Limits: the largest any single stock and any single sector may be. 5. Review: how often you will look, and what triggers a change.

Put it in your notes now. Every later module — reading the account, auditing diversification, surviving a drawdown, keeping score — measures your behaviour against these five lines.

Core and satellites

A widely used structure for someone learning to pick stocks is core and satellite. The core — often 70% to 80% of the money — sits in broad, low-cost index funds that own hundreds or thousands of companies. The satellites are a handful of smaller positions in individual stocks you have researched. The core does the heavy lifting; the satellites are where you practise judgement, and where a mistake cannot sink the whole account.

Here is one illustrative split of the $100,000. It is an example of the structure, not a recommended portfolio:

SleeveWeightDollars
Broad US index fund40%$40,000
Broad Canadian index fund20%$20,000
International developed-markets fund15%$15,000
Five individual stocks at 4% each20%$20,000
Cash reserve5%$5,000
Total100%$100,000

A portfolio that is all satellites — fifteen stocks and no core — is a valid thing to practise, but be clear that you are testing stock picking, not investing in general, and compare it against an index fund when you keep score.

Sizing each satellite from a risk budget

“4% each” in the table above was not arbitrary. The risk-budget method sizes a position from the damage you will accept if you are badly wrong, not from how much you like the company:

Position size (% of portfolio) = largest portfolio loss you accept from this one stock ÷ how far it could plausibly fall

If you are willing to lose 2% of the whole account on any single stock, and a given stock could plausibly fall 50%, the position is 2 ÷ 50 = 4% — $4,000 of $100,000. If it then does fall 50%, you lose $2,000: exactly the budget. A speculative stock that could go to zero gets 2 ÷ 100 = 2%. The riskier the holding, the smaller the position — the reverse of what excitement usually does.

The Manage Your Risk course covers this method in depth, including adjustments for volatility. For practice, one budget and one honest estimate of the downside are enough.

From dollars to shares

Orders are placed in shares, so the dollar size has to be converted:

Shares = dollar amount ÷ share price
Worked exampleYou want a $4,000 position in a stock trading at $187.50. $4,000 ÷ $187.50 = 21.33 shares. The simulator accepts the fractional amount. Many real brokers do not, or allow fractions only on selected stocks — in which case you buy 21 whole shares for $3,937.50 and leave $62.50 in cash. For very expensive shares the rounding matters: a $4,000 position in a $900 stock is either 4 shares ($3,600) or 5 ($4,500), a 10% or 12.5% miss on your intended size.

If you want your practice to match a broker without fractional shares, round down to whole shares in the simulator too.

Why keep cash at all

Cash earns nothing in the simulator, so it can look like a waste. It has three jobs. It lets you rebalance or add to a position after a fall without selling something else. It absorbs mistakes — a position sized too large can be trimmed without scrambling. And in a real account, a separate emergency fund is what stops a job loss from forcing you to sell investments at a bad moment.

A small reserve of 2% to 10% is common in practice portfolios. Whatever you choose, write the number into your plan so that “I’ll just put the rest in” is a decision, not a drift.

The currency problem

Because the simulator does no currency conversion, a TSX price in Canadian dollars and a US price in US dollars are added together as if they were the same money. A $100 US share and a $100 Canadian share each cost “$100” of your virtual cash, even though in reality — at an exchange rate of, say, 1.37 — the US share would cost about C$137.

For learning, pick the simplest honest option:

All at once, or in stages?

Once the plan is set, you can buy everything on day one or phase in over several months. Historically, investing a lump sum immediately has beaten spreading it out roughly two-thirds of the time in Vanguard’s long-run studies, simply because markets rise more often than they fall. Staging in reduces the regret of buying just before a drop, at the cost of usually earning a little less. Either is defensible. What matters for practice is choosing one in advance and writing it down.

Practice in Paper Trading

Your mission
  1. Write your five-line plan in the notes panel.
  2. Choose a currency approach: all-US, all-TSX, or mixed with the distortion noted.
  3. For each satellite stock, write down your risk budget and its plausible fall, and calculate the dollar size and share count.
  4. Place the trades in Paper Trading. Leave your planned cash reserve unspent.
  5. Check the Cash figure afterwards matches your plan to within a few hundred dollars.

Open Paper Trading →

💡 Research each satellite in Stock Research, check two candidates side by side in Compare, then build the portfolio in Paper Trading.

Educational purposes only; not financial advice. Paper trading is a simulation: no real money or securities are involved, and simulated results do not reflect the spreads, fees, currency conversion, taxes or emotions of real investing. Historical figures are illustrative and are not a forecast. Always do your own research and consult a licensed advisor.