Does implied volatility always rise as earnings announcements approach?
Changes in implied volatility are caused by many things, of course, and it is tough to isolate the effect you are describing, but let's try to generalize for a moment. Implied volatility is generally a measure of how much expect uncertainty there is about the future price of the stock.  Uncertainty generally is higher in periods including earnings announcements because it is significant new information about the company's fortunes can make for significant changes in the price. However, you could easily have the case where the earnings are good and for some reason the market is very certain that the earnings will be good and near a certain level.  In that case the price would rise, but the implied volatility could well be lower because the market believes that there will be no significant new information in the earnings announcement.
"I looked at data from Sept 2010 to present: Standard deviation is what shows the spread shape of returns over time, and it meanS that about 2/3 of the time, AAPL return was within +/- 1.65 higher/lower than the daily average return which was .21 %. Not sure where to go with this except to suggest that in fact, AAPL is more volatile than the S&P and even another random tech company. With time, I'd probably come up with a list of stock more volatile. I know that when I look at a list of stocks I track on Yahoo, there are always a few that are just as volatile on a given day.  Excel makes the above analysis easy to do for a given stock, and it's actually an interesting exercise, at least for me. Disclaimer - the shape of stock returns is not a bell curve, and STdev is just a best fit.  Edit - given more time to tinker on excel, it would be interesting to see how the stock's volatility tracked over the years, did it increase or does it feel that way due to the high price? A $20 swing on a $600 stock is the same as a $2 swing on a $60 stock, yet ""up $20"" sounds huge." Markets are definitely not efficient 100% of the time in thousands for ways. For example, why does implied volatility of options spike right before earnings when everyone already know the earnings date? Sentiment can also change in a blink of an eye based on analyst downgrades or a technical sell off. That said, most market inefficiencies are not salable. Its not possible to make a play off a illogical sell-off when your AUM can buy the company many times over. "Invest! Because you are young and have lots of time, I recommend opening an investment account and putting most (1000£?) or all in something like an S&P 500 index fund or ETF. Start building  your savings now because compound growth over time will build significant wealth. You can still invest the other 500£/mo in something a bit less volatile if you think you'll need the money in < 5 years. If you expect your income to continue to grow and you expect to have extra cash every month for the foreseeable future, I'd just put it all in an index fund. You can weather any temporary market swings, and in the worst-case scenario you can always sell a few shares if you need the cash. The advantage of an index fund is that it has very low fees and it's an ""invest-and-forget"" approach. You don't have to watch the market every day because your money will simply match the market. And in the long term the market does much better than most managed funds or ETFs. https://en.wikipedia.org/wiki/Index_fund" One of the often cited advantages of ETFs is that they have a higher   liquidity and that they can be traded at any time during the trading   hours. On the other hand they are often proposed as a simple way to   invest private funds for people that do not want to always keep an eye   on the market, hence the intraday trading is mostly irrelevant for   them. I am pretty sure that this is a subjective idea. The fact is you may buy GOOG, AAPL, F or whatever you wish(ETF as well, such as QQQ, SPY etc.) and keep them for a long time. In both cases, if you do not want to keep an on the market it is ok. Because, if you keep them it is called investment(the idea is collecting dividends etc.), if you are day trading then is it called speculation, because you main goal is to earn by buying and selling, of course you may loose as well. So, you do not care about dividends or owning some percent of the company. As, ETFs are derived instruments, their volatility depends on the volatility of the related shares. I'm wondering whether there are secondary effects that make the   liquidity argument interesting for private investors, despite not   using it themselves. What would these effects be and how do they   impact when compared, for example, to mutual funds? Liquidity(ability to turn cash) could create high volatility which means high risk and high reward. From this point of view mutual funds are more safe. Because, money managers know how to diversify the total portfolio and manage income under any market conditions. This is great, thank you. Can you think of any cases where expected return is greater than interest payments (like in #2) but the best choice would still be raise money through equity issuing? My intuition tells me this may be possible for an expensive company. Historical volatility of a stock is going to be based on past performance, basically its current trend.  That can be useful, but really is no indication of how it will perform in the future.  Especially with a big swing in the market. Now if you're talking about implied volatility (IV) of an options contract, that's a little different.  IV is derived from an option’s price and shows what the market “implies” about the stock’s volatility in the future. Thus it is based on the actions of active traders and market makers.  So, it gives you a bit more insight into what's going on, but at times has less to do with fundamentals. I guess a good way to think of IV based on options contracts is as an educated opinion, of the market as a whole, with regards to how much that stock could likely move over a period of time (options expiration). Also note that IV represents the potential for a stock to move, but it does not forecast direction. I don't know of any studies off the top of my head, but I'm sure there have been plenty. Option prices can predict the range of movement of the underlying, but not if the underlying is going up or down. An option price gives an implied volatility for an underlying . That IV number helps predict a range for the underlying price over the next few days,months, upto a year. In principle, the stock price should see no change in the days leading up to an earnings announcement, and then at the moment of the announcement, the stock price should move in the direction of the earnings surprise (relative to the market's belief of what earnings were going to be). In practice, stock prices tend to drift a little in the direction of the surprise shortly before the announcement and the associated price jump. This could be because smart investors were able to replicate the computations to predict the announcement or because information gets illegally leaked ahead of the announcement.  So I guess your bullet point B is a likely scenario. Note that hedging activity in the options market will not affect stock price one way or another.  Options transfer risk from one party to another but net to zero.  Intense hedging activity may be able to push up the price of options (increasing the implied volatility), but it shouldn't affect the price of a stock one way or the other. For this reason, bullet point A is not the case. Note that price behavior after the announcement is also interesting: it seems to take some time to reach the correct price instead of jumping directly to it as economists would predict.   This phenomenon is known as post earnings announcement drift.