Cerebras Systems raised $5.5 billion in its IPO on Thursday, pricing shares at $185 Wednesday evening, way higher than its range ($115 to $125, later raised to $150-$160), even as it increased the size of the offering to 30 million shares. It then opened to public trading at $385, more than double (up 108%), as retail investors bid up the price to grab them. The stock cooled only slightly soon after. It is currently trading heavily mid-day at above $330. Even at the IPO price of $185, the company entered its first day of trading at a fully-diluted valuation of $56.4 billion (meaning, accounting for all shares). Co-founder CEO Andrew Feldman’s stake at $185/share is worth nearly $1.9 billion, while co-founder CTO Sean Lie’s stake weighs in at about $1 billion. And obviously, if the above $300 price holds, the company and founders will end the day worth far more than that. A year ago, it looked like this day would never happen for Cerebras. The Nvidia competitor, which designed its giant chip from scratch, …