Trader consensus on Polymarket assigns a 99.8% implied probability to Elon Musk's net worth falling in the 640-650 billion range per the Bloomberg Billionaires Index close on March 31, 2026, reflecting the index's conservative $644 billion valuation after a daily +$11.7 billion (+1.8%) gain driven primarily by Tesla's (TSLA) share price appreciation amid sustained EV demand and AI integration momentum. Musk's ~11% Tesla stake plus 304 million exercisable options, combined with a 44% holding in the SpaceX-xAI entity (post-February merger, valued at ~$1 trillion with illiquidity discounts), anchor this positioning, bolstered by year-to-date +$24.2 billion growth. Realistic challenges include rare post-close revisions to private asset valuations or discrepancies with Forbes' higher $817 billion real-time estimate, though Bloomberg's daily post-NYSE methodology commands market trust.