Informed traders trade options on underlying securities to lower transaction costs and increase financial leverage for price trend and variance strategies. Options markets play a significant role in price discovery by incorporating private information about future prices for an underlying security into option prices. I generate a new model-free volatility measure to calculate the "distance from arbitrage bounds" from minute-by-minute option series for the S&P 500 index and 30 individual underlying stocks. These iron butterfly arbitrage bounds (IBBs) use intraday call and put option prices from the Bloomberg database. Narrow and wide IBBs are expected to reveal the options market valuation of volatility by market participants. Data series is gathered by using successive one-minute intervals from the Bloomberg database. The data comprise the most recent bid and ask option prices and volumes. I collect S&P 500 index values and index options and use 30 underlying stock prices and option prices for the contracts that have the largest option trading volume during the sampling interval. These bid and ask prices reflect the information generated by intraday price pressures implied by S&P 500 index options or stock options. Consistent with the option micro-structure literature, I find that the IBB measure for actively traded stock options attains its highest level immediately after the open of the market, declines steadily throughout the first trading hour and remains relatively stable until market close. However, index IBBs behave differently. S&P 500 index option IBB attains its lowest level during the first hour of the trading day, then increases and remains relatively stable until market close. I present new evidence regarding the dynamic relation between stock returns and innovations in expected volatility by using the minute-by-minute change in implied volatility (IV) as a proxy. Unlike the relationship between individual stock returns and their respective changes in implied idiosyncratic volatility, I find that all the coefficients on the market volatility index (VIX) term are negative and significant. Therefore, the evidence supports the explanation that the negative relationship between stock returns and expected volatility innovations is primarily related to the systematic component of the expected volatility. I also test whether narrow and wide IBB values capture incremental information to explain the return-volatility relationship. Results indicate that neither narrow IBB nor wide IBB values provide additional information beyond that provided by VIX and IV. The results are robust to five-minute and ten-minute sampling frequencies.