Every print on the SPX options tape carries an OPRA condition code naming the pipe it came through: electronic book, complex order book, price-improvement auction, a multi-leg order legging into the simple book, or a human being on the trading floor in Chicago. Nobody appears to have published the composition for SPX — the one product where the answer is unusual. So we tabulated five years of it, every code mapped, cancels excluded, zero unmapped residual.
The near book, by year (share of volume):
channel
electronic simple book
34.2%
