The Kelly Signal family (3Sig / 6Sig / 9Sig)
Jason Kelly · 2015
Quarterly value-averaging strategies that pursue a fixed 3%, 6%, or 9% quarterly target on a stock ETF while using a bond ETF as a cash buffer. The book's headline claim is that the strategy forces you to buy low and sell high, quarter after quarter. The backtest says otherwise.
How the strategy works (as written)
- Start and reset 3Sig at 80% IJR and 20% BND, the book's default plan, and 6Sig and 9Sig at 60% stock ETF and 40% bond ETF (3Sig ran 60/40 until 2026-10-13).
- The signal line compounds 3%, 6% or 9% per quarter and is never adjusted down.
- Each quarter, sell the surplus above the line into bonds or buy the shortfall from bonds.
- Cap buys at 90% of the current bond balance (Kelly's throttle), with our own floor: a buy never takes bonds below 10% of portfolio value.
- Under Kelly's 30 Down rule (6Sig and 9Sig only, as in his 2020 revision), when SPY closes a quarter at or below 70% of its 8-quarter rolling high, skip the next 2 sell signals while buys continue. SPY is the book's trigger and 2 skips is Kelly's latest count (February 2023; the book skipped 4, his April 2020 revision 1). Until 2026-10-13 our trigger watched the plan's own stock ETF.
- After a sell quarter, reset to the base allocation when bonds exceed 30% of portfolio value: back to 80/20 for 3Sig, the book's rebalancing threshold, and to 60/40 for 6Sig and 9Sig, where applying it is our extension.
- For 9Sig, apply a spike reset to 60/40 after a quarter in which TQQQ gained 100% or more.
Our backtest, honest implementation
| Variant | CAGR | Max DD | Sharpe | Vol |
|---|---|---|---|---|
| 3Sig (IJR / BND) 1985-05 to 2026-10 (41.4 years) | 10.3% | -54.9% | 0.64 | 19.0% |
| 6Sig (MVV 2x mid-cap / AGG) 1985-05 to 2026-10 (41.4 years) | 15.1% | -82.9% | 0.61 | 35.8% |
| 9Sig (TQQQ 3x Nasdaq / AGG) 1985-05 to 2026-10 (41.4 years) | 19.1% | -99.8% | 0.60 | 62.5% |
Kelly metrics are a snapshot as of 2026-10-15, with data through 2026-10-14, measured under the rules since the 2026-10-13 change (30 Down on SPY, 3Sig at the book's 80/20), with volatility on observed prices; the strategy pages carry the live numbers. For context, the public comparison endpoint on 2026-09-11 reports S&P 500 buy-and-hold since 1920-01 at 10.0% CAGR, -83.7% max drawdown and 0.61 Sharpe, and Classic 60/40 (SPY/AGG) since 1920-02 at 8.0% CAGR, -65.8% max drawdown and 0.73 Sharpe. These are full-history benchmarks with different measurement windows from the Kelly backtests, not matched-period comparisons.
Why we do not recommend it
Closed-system backtest flaw (the critical one)
The book's own examples assume periodic cash infusions from the investor's salary to replenish the bond sleeve. Our closed-system backtests use no new money, so they do not reproduce that contribution assumption. After a severe drawdown, repeated buys can shrink the reservoir toward our bond floor, limiting further purchases even while the signal line calls for more stocks.
The signal line never resets downward
The target value for the stock sleeve compounds forward at 3%, 6% or 9% per quarter regardless of what the market has actually done. After a crash, the target can sit far above the stock sleeve's value. Kelly's throttle and our bond floor limit purchases, so the portfolio may remain below target without fresh contributions or a recovery.
The reservoir has no refill in a long bear market
In a closed system, refills come only from sell signals. Deep in a bear market there are no surpluses to sell, and the 30 Down window then skips the first sell signals of the recovery. The throttle and floor slow the bleed without creating a refill.
Leveraged variants (6Sig/9Sig) are path-dependent traps
MVV is 2x daily mid-cap. TQQQ is 3x daily Nasdaq. Both suffer volatility decay on top of the mechanical flaws above. Our 9Sig backtest shows -99.8% max drawdown over 1985-05 to 2026-10 (41.4 years), a near-total loss despite the throttle and bond floor.
It does not beat simple buy-and-hold on risk-adjusted terms
9Sig's 0.60 Sharpe trails both the S&P 500's 0.61 and Classic 60/40's 0.73, so its aggression buys no risk-adjusted improvement in these full-history results. The benchmark histories begin in 1920-01 and 1920-02 respectively, while the Kelly backtests begin in 1985-05, so this is not a matched-period comparison. Unleveraged 3Sig at the book's 80/20 does only slightly better: its 0.64 Sharpe edges the S&P 500's 0.61 but still trails Classic 60/40's 0.73.
Verdict
We keep the three Kelly variants listed as 'Educational only' because we implemented them honestly and we want readers to be able to compare them directly to the strategies we do endorse. But we have never run them with real money, and we recommend that you don't either. If you like value-averaging as an idea, use it for contributions (adding new money to a target), not as a rebalancing rule for a closed portfolio.
Source
Jason Kelly, "The 3% Signal: The Investing Technique That Will Change Your Life" (Plume, 2015) and later variants.