What do stock market index future bid/ask quotes mean?
"Well, futures don't have a ""strike"" like an option - the price represents how much you're obligated to buy/sell the index for at a specified date in the future.  You are correct that there's no cost to enter a contract (though there may be broker fees and margin payments).  Any difference between the contract price and the price of the index at settlement is what is exchanged at settlement.   It's analogous to the bid/ask on a stock - the bid price represents the price at which someone is willing to ""buy"" a futures contract (meaning enter into a long position) and the ask is how much someone is willing to ""sell"" a contract. So if you want to take a long position on S&P500 mini futures you'd have to enter in at the ""ask"" price.  If the index is above your contract price on the future expiry date you'll make a profit; if it is below the contract price you'll take a loss."
The equation you show is correct, you've simply pointed out that you understand that you buy at the 'ask' price, and later sell at the 'bid.' There is no bid/ask on the S&P, as you can't trade it directly.  You have a few alternatives, however - you can trade SPY, the (most well known) S&P ETF whose price reflects 1/10 the value or VOO (Vanguard's offering) as well as others. Each of these ETFs gives you a bid/ask during market hours. They trade like a stock, have shares that are reasonably priced, and are optionable.  To trade the index itself, you need to trade the futures. S&P 500 Futures and Options is the CME Group's brief info guide on standard and mini contracts.  Welcome to SE. You have to look at stocks just like you would look at smaller and more illiquid markets. Stock trade in auction markets. These are analogous to ebay or craigslist, just with more transparency and liquidity. There is no guarantee that a market will form for a particular stock, or that it will sustain.  When a stock sells off, and there are no bids left, that means all of the existing bidder's limit orders got filled because someone sold at those prices. There is nothing fishy about that. It is likely that someone else wants to sell even more, but couldn't find any more bidders. If you put a bid you would likely get filled by the shareholder with a massive position looking for liquidity. You could also buy at the ask. "First, what structure does your index fund have?  If it is an open-end mutual fund, there are no bid/ask spread as the structure of this security is that it is priced once a day and transactions are done with that price.  If it is an exchange-traded fund, then the question becomes how well are authorized participants taking advantage of the spread to make the fund track the index well?  This is where you have to get into the Creation and Redemption unit construct of the exchange-traded fund where there are ""in-kind"" transactions done to either create new shares of the fund or redeem out shares of the fund.  In either case, you are making some serious assumptions about the structure of the fund that don't make sense given how these are built. Index funds have lower expense ratios and are thus cheaper than other mutual funds that may take on more costs.  If you want suggested reading on this, look at the investing books of John C. Bogle who studied some of this rather extensively, in addition to being one of the first to create an index fund that became known as ""Bogle's Folly,"" where a couple of key ones would be ""Common Sense on Mutual Funds: New Imperatives for the Intelligent Investor"" and ""Bogle on Mutual Funds: New Perspectives for the Intelligent Investor."" In the case of an open-end fund, there has to be a portion of the fund in cash to handle transaction costs of running the fund as there are management fees to come from running the fund in addition to dividends from the stocks that have to be carefully re-invested and other matters that make this quite easy to note.  Vanguard 500 Index Investor portfolio(VFINX) has .38% in cash as an example here where you could look at any open-end mutual fund's portfolio and notice that there may well be some in cash as part of how the fund is managed.  It’s the Execution, Stupid would be one of a few articles that looks at the idea of ""tracking error"" or how well does an index fund actually track the index where it can be noted that in some cases, there can be a little bit of active management in the fund. Just as a minor side note, when I lived in the US I did invest in index funds and found them to be a good investment.  I'd still recommend them though I'd argue that while some want to see these as really simple investments, there can be details that make them quite interesting to my mind. How is its price set then? The price is computed by taking the sum value of all the assets of the fund minus the liabilities and divided by the number of outstanding shares.  The price of the assets would include the closing price on the stock rather than a bid or ask, similar pricing for bonds held by the fund, derivatives and cash equivalents.  Similarly, the liabilities would be costs a fund has to pay that may not have been paid yet such as management fees, brokerage costs, etc. Is it a weighted average of all the underlying stock spreads, or does   it stand on its own and stems from the usual supply & demand laws ? There isn't any spread used in determining the ""Net Asset Value"" for the fund.  The fund prices are determined after the market is closed and so a closing price can be used for stocks. The liabilities could include the costs to run the fund as part of the accounting in the fund, that most items have to come down to either being an asset, something with a positive value, or a liability, something with a negative value. Something to consider also is the size of the fund.  With over $7,000,000,000 in assets, a .01% amount is still $700,000 which is quite a large amount in some ways." "Following comments to your question here, you posted a separate question about why SPY, SPX, and the options contract don't move perfectly together.  That's here Why don't SPY, SPX, and the e-mini s&p 500 track perfectly with each other? I provided an answer to that question and will build on it to answer what I think you're asking on this question.  Specifically, I explained what it means that these are ""all based on the S&P.""  Each is a different entity, and different market forces keep them aligned.  I think talking about ""technicals"" on options contracts is going to be too confusing since they are really a very different beast based on forward pricing models, so, for this question, I'll focus on only SPY and SPX. As in my other answer, it's only through specific market forces (the creation / redemption mechanism that I described in my other answer), that they track at all.  There's nothing automatic about this and it has nothing to do with some issuer of SPY actually holding stock in the companies that comprise the SPX index. (That's not to say that the company does or doesn't hold, just that this doesn't drive the prices.)  What ever technical signals you're tracking, will reflect all of the market forces at play.  For SPX (the index), that means some aggregate behavior of the component companies, computed in a ""mathematically pure"" way.  For SPY (the ETF), that means (a) the behavior of SPX and (b) the behavior of the ETF as it trades on the market, and (c) the action of the authorized participants.  These are simply different things. Which one is ""right""?  That depends on what you want to do.  In theory you might be able to do some analysis of technical signals on SPY and SPX and, for example, use that to make money on the way that they fail to track each other.  If you figure out how to do that, though, don't post it here.  Send it to me directly. :)" This fortune article is referenced in his either 2003 or 2004 annual report in which he does say that the market will not likely return much in the future and generally talks numbers. I am also a value investor, such that I can be in this environment and believe there is a bit of value in knowing where you think the market is headed but the real value is in underwriting each deal. In long, I agree with you "At the most fundamental level, every market is comprised of buyers and selling trading securities. These buyers and sellers decide what and how to trade based on the probability of future events, as they see it. That's a simple statement, but an example demonstrates how complicated it can be. Picture a company that's about to announce earnings. Some investors/traders (from here on, ""agents"") will have purchased the company's stock a while ago, with the expectation that the company will have strong earnings and grow going forward. Other agents will have sold the stock short, bought put options, etc. with the expectation that the company won't do as well in the future. Still others may be unsure about the future of the company, but still expecting a lot of volatility around the earnings announcement, so they'll have bought/sold the stock, options, futures, etc. to take advantage of that volatility.  All of these various predictions, expectations, etc. factor into what agents are bidding and asking for the stock, its associated derivatives, and other securities, which in turn determines its price (along with overall economic factors, like the sector's performance, interest rates, etc.) It can be very difficult to determine exactly how markets are factoring in information about an event, though. Take the example in your question. The article states that if market expectations of higher interest rates tightened credit conditions... In this case, lenders could expect higher interest rates in the future, so they may be less willing to lend money now because they expect to earn a higher interest rate in the future. You could also see this reflected in bond prices, because since interest rates are inversely related to bond prices, higher interest rates could decrease the value of bond portfolios. This could lead agents to sell bonds now in order to lock in their profits, while other agents could wait to buy bonds because they expect to be able to purchase bonds with a higher rate in the future.  Furthermore, higher interest rates make taking out loans more expensive for individuals and businesses. This potential decline in investment could lead to decreased revenue/profits for businesses, which could in turn cause declines in the stock market. Agents expecting these declines could sell now in order to lock in their profits, buy derivatives to hedge against or ride out possible declines, etc. However, the current low interest rate environment makes it cheaper for businesses to obtain loans, which can in turn drive investment and lead to increases in the stock market. This is one criticism of the easy money/quantitative easing policies of the US Federal Reserve, i.e. the low interest rates are driving a bubble in the stock market. One quick example of how tricky this can be. The usual assumption is that positive economic news, e.g. low unemployment numbers, strong business/residential investment, etc. will lead to price increases in the stock market as more agents see growth in the future and buy accordingly. However, in the US, positive economic news has recently led to declines in the market because agents are worried that positive news will lead the Federal Reserve to taper/stop quantitative easing sooner rather than later, thus ending the low interest rate environment and possibly tampering growth.  Summary: In short, markets incorporate information about an event because the buyers and sellers trade securities based on the likelihood of that event, its possible effects, and the behavior of other buyers and sellers as they react to the same information. Information may lead agents to buy and sell in multiple markets, e.g. equity and fixed-income, different types of derivatives, etc. which can in turn affect prices and yields throughout numerous markets." "I always liked the answer that in the short term, the market is a voting machine and in the long term the market is a weighing machine. People can ""vote"" a stock up or down in the short term.   In the long term, typically, the intrinsic value of a company will be reflected in the price. It's a rule of thumb, not perfect, but it is generally true. I think it's from an old investing book that talks about ""Mr. Market"".   Maybe it's from one of Warren Buffet's annual letters.    Anyone know? :)" In the world of stock exchanges, the result depends on the market state of the traded stock. There are two possibilities, (a) a trade occurs or (b) no trade occurs. During the so-called auction phase, bid and ask prices may overlap, actually they usually do. During an open market, when bid and ask match, trades occur.