E214: SpaceX soars to $400B valuation; Revolut banks on $65B valuation boost; Groq chips in at $6B valuation; Mistral AI storms to $1B+ raise; Harmonic AI tunes up to $875M valuation; xAI unleashes Grok 4 at PhD-level smarts; X's Yaccarino exits after X m

This Week in Pre-IPO Stocks - E214: SpaceX soars to $400B valuation; Revolut banks on $65B valuation boost; Groq chips in at $6B valuation; Mistral AI storms to $1B+ raise; Harmonic AI tunes up to $875M valuation; xAI unleashes Grok 4 at PhD-level smarts; X's Yaccarino exits after X m