Investors kept buying the AI stock even after insiders stopped selling.Shares of Palantir (PLTR 0.63%) gained 11.7% in October, according to data provided by S&P Global Market Intelligence. The AI stock surged higher following the reported end of a major insider trade. Momentum ahead of its November earnings report seems to have kept demand robust as the supply of shares dropped.Major insider selling concluded in October.Palantir's billionaire founder Peter Thiel initiated a mass sale of more than $1 billio ...