Some investors are valuing Elon Musk's Neuralink at $42 billion

Neuralink cofounder Elon Musk. Fabrice COFFRINI / AFP via Getty Images Investors are valuing the brain chip startup Neuralink at $42 billion in secondary markets. Neuralink was last valued at $9 billion in a funding round over a year ago. Since then, Musk has led a blockbuster SpaceX IPO, which is now worth $1.7 trillion. Demand for a piece of anything related to Elon Musk is booming. The near-trillionaire's brain chip startup, Neuralink, is being valued as high as $42 billion in recent…