Alibaba Group Holding Ltd. is leading a financing round of at least $600 million for Chinese AI startup MiniMax, spearheading its second major deal in the space this year as it unleashes capital in pursuit of growth.The two-year-old firm has secured funds from Alibaba and other investors at a valuation of more than $2.5 billion, according to people familiar with the matter. The fundraise remains in progress but Alibaba and HongShan, formerly Sequoia China, have committed to the financing, one of...