Handley (2001) describes how to value variable purchase options (VPO). A VPO is basically a call option, but where the number of underlying shares is stochastic rather than fixed, or more precisely, a deterministic function of the asset price. The strike price of a VPO is typically a fixed discount to the underlying share price at maturity. The payoff at maturity...
![WMT: Variable Purchase Options [Loxx]](https://s3.tradingview.com/0/0xhjnrFz_mid.png "Variable Purchase Options [Loxx]")
