The daily game is the Tape — execution, costs, behavior. Cycle Mode is the Allocation — judgment across full market cycles. Tactics are not strategy.
Risk-adjusted return
Predict
Which trader is better, risk-adjusted?
Do
Illustrative scores: excess return ÷ volatility. A: 40 ÷ 45 = 0.89. B: 12 ÷ 10 = 1.20.
A return without its risk is a story, not a result. Professionals judge a return against the danger taken to earn it — the classic version divides excess return by volatility (the Sharpe ratio). That's why Achilles Desk grades your Achilles Score, not your raw profit.
Steady beats spectacular.
Drawdown math
Predict
Before you drag — a 20% loss needs what gain to break even?
Reveal the answer
A 20% loss needs a 25% gain to break even.
Do
Drag the slider. The tick marks appear once you start.
Gain needed to break even
needed gain = loss ÷ (1 − loss)
A drawdown is the fall from your peak — and losses are asymmetric. The deeper the hole, the steeper the climb, because you rebuild from a smaller base. Professionals fear drawdowns more than they chase wins.
Asymmetry punishes the careless.
Sources
- Fidelity — What is a drawdown
- Achilles Desk coach note CN1 (drawdown cost, computed from your match)
Margin calls
Predict
Before you drag — at what fall does the margin call hit?
Reveal the answer
The margin call fires at a 33.3% fall.
Do
You have $100,000. You borrow $100,000 more to buy stock — a $200,000 position, the 50% initial-margin maximum.
Equity
Maintenance 25% — the FINRA minimum cushion on the position's value.
MARGIN CALL
Level 1 — deposit cash or sell.
The broker sells your positions at market to repay the loan. You keep what's left — but the choice of what to sell is gone.
Margin is borrowed money, and borrowed money has rules. Your broker demands a minimum cushion — maintenance margin, at least 25% of the position's value — and a falling market eats it fast, because the loan doesn't shrink when prices do. Leverage magnifies gains; it also manufactures fragility.
The real case
In March 2023, Silicon Valley Bank's long-dated bond book — carried at $91.3B against a fair value of $76.2B — met a $42B one-day depositor run. Regulators closed the bank the next morning.
Margin calls don't negotiate.
Sources
- U.S. SEC Investor Bulletin on margin accounts
- Bhat & Desai (2023) on SVB
- CNBC on the $42B run
- Achilles Desk coach note CN3 (margin call, explained)
Fee drag
Predict
12 trades a month at $8 a trade costs what per year?
Reveal the answer
$1,152 a year.
Do
At the default $8: illustrative model of $5 commission + $0.03/share spread on a 100-share order.
Your annual drag
Commission + spread only — impact and borrow fees not modeled.
Every trade pays four tolls: commission, the bid-ask spread, market impact, and borrow fees on shorts. Each looks tiny; across dozens of trades a month they become a second portfolio working against you. Costs are the one return-killer you control.
Frequency is the silent tax.
Sources
- U.S. SEC glossary — Ask price
- Morningstar — Bid-Ask Spread
- Achilles Desk coach note CN4 (fee drag)
Diversification
Predict
Largest holding 50%, shock −50%: the portfolio loses…
Do
The game caps any holding at 25 percent.
Portfolio loss
Diversification is the only free lunch in investing: spread risk so no single position can end you. That's why the game enforces a 25% single-issuer cap. Combine assets that don't move together and portfolio risk falls — the intuition is older than the math: don't let one mistake be fatal.
Concentration is a choice.
Sources
- U.S. SEC — Diversify Your Investments
- Markowitz (1952), Journal of Finance (text citation)
- Achilles Desk coach note CN5 (concentration)
The Trap
Predict — your decision
A guru shows you a pattern (illustrative chart — not real data): every time this shape appeared, the stock jumped. Would you trade it?
See
Cost autopsy: after commissions, spread, slippage, and one surprise earnings call, the edge is gone. And when 7,846 rules were tested on 100 years of data, the winners were mostly luck.
See
You asked for the test before risking the money. The pattern still has to survive costs, slippage, and data-snooping correction.
If you traded it…
Cost autopsy: after commissions, spread, slippage, and one surprise earnings call, the edge is gone. And when 7,846 rules were tested on 100 years of data, the winners were mostly luck.
If you walked away…
You asked for the test before risking the money. The pattern still has to survive costs, slippage, and data-snooping correction.
A chart pattern is a claim about the future, and claims need tests — after costs, after slippage, on data the rule never saw. The trap isn't the indicator; it's weak evidence.
Untested patterns are expensive.
Sources
- Sullivan, Timmermann & White (1999), Journal of Finance
- Trap Crucible: mandatory, autopsy-only (panel findings)
The Fear Gauge
Predict
VIX reads 35. What are options traders pricing in?
Do
VIX
Normal
healthy uncertainty
High fear, big size.
In the game, this is when Heat discipline matters most.
The VIX — Wall Street's "fear gauge" — measures annualized expected 30-day volatility for the S&P 500, priced from SPX index options. When it spikes, investors pay up for protection, which is exactly when protection costs the most. The game labels every tape calm, normal, stressed, or crisis.
Volatility sets the position size.
Sources
- Cboe — VIX options overview
- Fidelity — What is the VIX
- Achilles Desk LO7 (Fear Gauge / regime labels)
Splits & dividends
Predict
2-for-1 split at $100. Your $1,000 holding is now worth…
Do
You own 10 shares at $100 = $1,000.
10 shares at $100. Dividends pay $2/share ($1 after a split).
A split changes the slice count, never your value. Dividends pay cash for holding; the price adjusts on the ex-date, the first day the stock trades without it. Short the stock and you owe cash in lieu of the dividend to the share lender — one of the quiet costs of betting against a stock.
Corporate actions are arithmetic.
Sources
- U.S. SEC glossary — Stock Split
- Achilles Desk LO8 (corporate actions)
Compounding vs the hurdle
Predict
$100/month for 40 years at 7% ends at roughly…
Reveal the answer
Roughly $262,000 — most of it from compounding, not contributions. (Markets don't promise 7%.)
Do
At 7%
At the T-bill hurdle (~4%)
You contributed
The gap between the two is the opportunity cost of playing it safe. Fixed 7% illustration rate — markets don't promise 7%. Check the official math → U.S. SEC compound interest calculator.
Compounding is growth on growth — returns earning their own returns. $100 a month for 40 years at 7% becomes roughly a quarter-million dollars, most of it from compounding, not contributions. And cash isn't idle: it earns the T-bill rate — the "do nothing" alternative every investment, and your game score, is measured against.
Compounding rewards the patient.
Sources
- U.S. SEC — Compound Interest
- U.S. SEC compound interest calculator
- Achilles Desk LO9 (compounding and the hurdle)
Know your biases
Check yourself — three scenarios. No score, no grade; just notice what you'd do.
Your biggest costs aren't crashes — they're your own behavior: trading too much, selling winners early while riding losers, sizing on gut feel. Researchers can measure these patterns in brokerage records. The gap between the market's return and yours is where the entire lesson lives.
Discipline is the only edge you own.
Sources
- Odean (1998), Journal of Finance
- Achilles Desk LO10 / coach note CN6 (overtrading)
The path. T0 — Start where you are. No prerequisites. · T1 — Paper-trade the tape. · T2 — Earn your capital. · T3 — Size the book.
The loop. Learn the idea → Try it on the tape → Feel the friction → Keep the lesson.
Achilles Desk — the turn-based trading simulation these ideas are built for — is in development. The Center grows with it.
Common questions
Is Achilles Desk live yet?
Not yet — the game is in development. The Education Center is live now so the ideas arrive first. Leave your email on the Trading Simulation tab and we'll notify you at launch.
Do I need investing experience?
No. The Center starts at zero — no prerequisites. Each instrument teaches one idea by letting you operate it, not by asking you to read about it.
Is this financial advice?
No. Everything here is educational. Nothing on this page is investment advice, a recommendation, or an offer to buy or sell any security.
Will the game be free?
The plan is free at launch — no pay-to-win, no loot boxes, no entry fees, and no real-money wagering.
Can I use this in a classroom?
Teachers are welcome to use the instruments with students. Everything runs in the browser — no account, no signup.