Nexthop AI, an artificial intelligence infrastructure startup, has raised $500 million in a deal led by Lightspeed Venture Partners, part of a surge of investments in players building out AI capacity.Nexthop, which builds networking hardware and software for AI data centers, hit a $4.2 billion valuation with the new funding round, it plans to announce Tuesday. Andreessen Horowitz joined the funding, alongside all of the company’s existing investors, including Altimeter Capital and Kleiner Perkin...