Homegrown e-commerce platform Flipkart's valuation may double to $20 billion if US-headquartered retail giant Walmart invests in the company. Walmart is reportedly planning to spend $5-10 billion for a substantial stake in Flipkart, making it one of the largest cross-border deals in India. At present, SoftBank is the largest shareholder in Flipkart with a 23.6% stake.