Anil Ambani-led Reliance Capital on Thursday said it has invited joint venture partner Nippon Life Insurance to buy its entire 42.88% stake in Reliance Nippon Life Asset Management (RNAM). Japan's Nippon Life already holds a 42.88% stake in RNAM, India's first listed mutual fund company. RNAM shares surged 20% on Thursday, taking the company's market value to nearly ₹11,500 crore.