Polymarket traders have priced a 100% implied probability for Microsoft (MSFT) shares closing the week of April 13 above $420, reflecting ironclad consensus driven by a historic four-day rally that propelled the stock from $384 on April 13 to $422.79 by April 17 close. This surge stemmed from CEO Satya Nadella's AI strategy update, OpenAI's major Codex enhancement boosting Microsoft's cloud ecosystem, and bullish analyst reiterations projecting 21% fiscal 2026 earnings growth to $16.50 per share amid accelerating Azure revenue. Broader tech sector momentum and dip-buying after early-2026 weakness further entrenched gains, with shares now testing key resistance levels. Realistic challenges include a sudden macroeconomic shock or pre-earnings (April 29) profit-taking, though proximity to resolution minimizes downside risk.