An equity holder gets the upside; a bondholder gets their coupon back, at best. That payoff asymmetry makes credit investors professionally paranoid — they are paid to obsess over the downside, because it's the only side they have. When the market's most downside-sensitive participants start demanding more compensation to hold corporate risk, spreads widen. That widening is a price, set by people whose entire job is smelling trouble.
History is generous with examples. Credit spreads began deteriorating in mid-2007, months before equity indices peaked. The same pattern — credit cracking first, equities catching down later — repeats often enough that "watch the credit market" has been professional folklore for generations. Folklore, however, isn't a rule, so we tested it.
The idea is simple to state: hold equities while the equity trend is up and credit is calm; step aside when either breaks. Two independent tripwires, one of which — credit — tends to fire early precisely because of who sets its price.
The equity trend tells you what stocks are doing. The credit spread tells you what the people with no upside think happens next.
We ran that rule over fifteen years of S&P 500 data with a forty-year credit series and published the full result on the site. The shape of the outcome, which is what matters here: the overlay gave up a meaningful share of buy-and-hold's total return — and cut the maximum drawdown by roughly two-thirds, roughly doubling the risk-adjusted return. It also improved on the pure trend rule, which is the real test: credit added information the price trend didn't have.
We treat credit as one of four independent lenses precisely because it's fallible alone and valuable in combination — a second opinion from a witness with different incentives.
Open the live credit gauge and backtest →