STAMFORD — Point72 Ventures, billionaire hedge fund investor Steven Cohen’s venture capital business, announced Wednesday it was helping to lead a $11 million investment in Manhattan-based financial-technology firm Extend. The “Series A” fundraising, which was co-led by Manhattan venture-capital firm FinTech Collective, would support the growth of Extend, whose services focus on allowing cardholders and certain recipients to securely and instantly send and receive temporary “virtual” credit cards. “Growing customer expectations are driving fintech startups and financial institutions to develop and deliver more dynamic, feature-rich digital payments experiences for their customers,” Ventures partner Tripp Shriner said in a statement.