Stocks extended their decline for a third straight session on Tuesday (Aug. 18), renewing debate over the durability of the equity rally at a moment when rising Treasury yields, persistent inflation concerns, and a still‑simmering conflict with Iran threaten to keep pressure on risk assets. Short‑term market direction is unknowable, but several indicators are worth watching to gauge how resilience is evolving and if the current setback is an early clue of deeper trouble ahead.