Much attention has been devoted to understanding and modeling the dynamics of implied volatility curves and surfaces. This is crucial for both trading, pricing and risk management of option positions. We suggest a simple, yet flexible, model, based on a discrete and linear Kalman filter updating of the volatility skew. From a risk management perspective, we assess whether this model is capable of producing good density forecasts of daily returns on a number of option portfolios. We also compare our model to the sticky-delta and the vega–gamma alternatives. We find that it clearly outperforms both alternatives, given its ability to easily account for movements of different nature in the volatility curve.

In this paper, we examine leasing as a tax‐arbitrage instrument. Analysis of a sample of UK leases presented in this paper suggests that lessors earn large positive NPVs. Our theoretical model seeks to explain these positive NPVs in terms of a market price for a scarce resource that we identify as scarce taxable earnings. Using these prices, the model permits a lessor to determine whether the profitability of a proposed set of lease contracts can be improved by writing a different set of contracts that makes better use of the lessor's taxable earnings. There may be two reasons why an initial portfolio of contracts may be suboptimal. Either there may be clienteles or the leasing market may be inefficient. Subsequently, we discuss reasons why the leasing market may be characterized by clienteles, and, using two different samples of leases, we test whether the leasing market is segmented and efficient.