CASH-SETTLEMENT, EUROPEAN-STYLE EXERCISE Like SPX and most other index options, and unlike SPY and other ETF options. No risk of early assignment and loss of dividends, no portfolio disruption on assignment. CBOE Circulars (RG99-09 and RG00-171) allow SPX options to be written on a "covered" basis against SPY or IVV ETF shares in a margin account, provided the investor's brokerage firm has such policies in place http://www.cboe.com/micro/weeklys/SPXWeeklys.aspx