These two April 2026 Polymarket predictions test fundamentally different domains: domestic monetary policy versus geopolitical regime stability. The Fed interest rate market asks a direct economic question: will the Federal Reserve raise its policy rate by at least 25 basis points following its April meeting? The Iran regime market probes a high-impact geopolitical tail event: complete collapse of the Iranian government within a single month. Both markets touch on system-level risk—one through inflation dynamics and capital markets sensitivity to policy changes, the other through acute geopolitical disruption—yet they operate through entirely separate causal chains and information sets. At 0% YES across both markets, traders are pricing near-zero probability for either outcome by April 30. For the Fed hike, the floor price likely reflects post-March macro data and forward guidance consensus; the Fed typically signals intention in advance, and market expectations already price in low probability of surprise April action given the current inflation and employment picture. The 0% on Iran regime fall is more straightforward: regime collapse is a low-frequency, high-impact event, and a 30-day execution window is extraordinarily constrained. Both prices illustrate how Polymarket distinguishes between "low probability" and "impossible within the timeframe"—traders aren't saying regime collapse is impossible in absolute terms, but rather impossible to achieve by April 30. These outcomes would almost certainly move independently. Fed monetary policy responds to domestic labor markets, inflation metrics, and financial conditions; Iranian regime stability depends on internal political dynamics, military cohesion, and international pressure. A causal link between them is tenuous at best. The only plausible indirect correlation would flow through energy markets: if Middle East escalation triggered oil shocks and secondary inflation waves, the Fed might face different policy pressures by May. But this chain is speculative and second-order; base cases assume the markets evolve on separate tracks. For the Fed market, traders should monitor April's employment reports, inflation releases (PCE and CPI), Fed fund futures, and any unexpected financial conditions shock. Watch Fed speakers' commentary for signaling shifts and track 2-year yields as a real-time Fed policy guide. For Iran, follow internal political destabilization, military defection signals, and any escalation scenarios—but recognize that even rapid instability would face a steep technical climb to reach regime collapse by month-end. The comparison underscores a key insight: both markets sit at 0% not because traders dismiss these events entirely, but because they're pricing the probability across the full outcome distribution while compressing it across an extremely tight time window.