Index Versus ETF Option Pricing

Are there differences in implied volatilities (option pricing) between major indexes and the exchange-traded funds (ETF) that track them? In their 2011 paper entitled “The Implied Volatility of ETF and Index Options”, Stoyu Ivanov, Jeff Whitworth and Yi Zhang compare implied volatilities of SPDR Dow Jones Industrial Average (DIA), SPDR S&P 500 (SPY) and PowerShares QQQ (QQQ) to those of the Dow Jones Industrial Average (DJIA), the S&P 500 Index and the NASDAQ 100 Index, respectively. They note that ETF prices may deviate from underlying index levels because: (1) ETFs incorporate trading frictions from rebalancing and management fees; (2) ETF composition may differ slightly from that of the underlying index due to trading cost constraints; (3) ETFs accumulate dividends in a non-interest bearing account for periodic lump sum distribution; and, (4) ETFs trade until 4:15 p.m., while indexes close at 4:00 p.m. Also, index options are European, while ETF options are American. Using index levels at the close and ETF prices within one second of 4:00 p.m. during 3/10/99 through 12/29/06, and associated ETF and index near-to-expiration options price data filtered for reliability during 2003 through 2006, they find that: (more…)