01Start from a hypothetical evidence pack
Suppose inflation is reported at 3.3% versus a documented 3.0% expectation. Over a comparable window, 2Y yield rises from 4.00% to 4.25%, 10Y from 4.20% to 4.30%, a stock index loses 1%, the dollar strengthens and high-yield spreads widen 20 bps. These inputs are an educational scenario, not today’s observations. Calculate first: 2Y +25 bps, 10Y +10 bps, slope from +20 to +5 bps. This is bear flattening by 15 bps.
02Explain a plausible mechanism and test it
One explanation is that investors price a tighter future policy path. Higher discount rates can reduce equity present values and relative yield changes can support the dollar. Wider credit spreads could reflect concern that tighter conditions hurt weaker borrowers. But simultaneity is not proof. Check whether the inflation surprise, positioning, earnings news, auction supply or another event best explains the timing. For a duration-5 bond, +10 bps suggests roughly −0.5% from that yield shift alone.
03State scenarios and what changes your mind
Base case: persistent inflation keeps financing conditions restrictive; monitor subsequent core inflation, wages and central-bank communication. Alternative: a temporary component caused the surprise and growth weakens, reversing the rate move. Adverse case for risky assets: inflation remains sticky while growth deteriorates and credit losses rise. Avoid attaching precise probabilities without a method. End a brief with the key uncertainty, the next dated evidence to verify and how that evidence would alter the thesis.