What risk of a diversified portfolio can be specifically offset by options?
Options are contractual instruments. Most options you'll run into are contracts which allow you to buy or sell stock at a given price at some time in the future, if you feel like it (it gives you the option). These are Call and Put options, respectively (for buying the stock and selling the stock). If you have a lot of money in an index fund ETF, you may be able to protect your portfolio against a market decline by (e.g.) buying Put options against the ETF for a substantially lower price than the index fund currently trades at. If the market crashes and your fund falls in value significantly, you can exercise the options, selling the fund at the price that your option has specified (to the counter-party of your contract). This is the risk that the option mitigates against. Even if you don't have one particular fund with your investments, you could still buy a put option on a similar fund, and resell it to another person in lieu of exercise (they would be capable of buying the stock and performing the exercise themselves for profit if necessary). In general, if you are buying an option for safety, it should be an option either on something you own, or something whose price behavior will mimic something you own. You will note that options are linked to the price of stocks. Futures are contracts whose values are linked to the price of other things, typically commodities such as oil, gold, or orange juice. Their behaviors may diverge. With an option you can have a contractual guarantee on the exact investment you're trying to protect. (Additionally, many commodities' value may fall at the same time that stock investments fall: during economic contractions which reduce industrial activity, resulting in lower profits for firms and less demand for commodities.) You may also note that there are other structures that options may have - PUT options on index funds or similar instruments are probably most specifically relevant to your interests. The downside of protecting yourself with options is that it costs money to buy this option, and the option eventually expires, so you may lose money. Essentially, you are buying safety and risk-tolerance from the option contract's counterparty, and safety is not free. I cannot inform you what level of safety is appropriate for your portfolio's needs, but more safety is more expensive. "As I stated in my comment, options are futures, but with the twist that you're allowed to say no to the agreed-on transaction; if the market offers you a better deal on whatever you had contracted to buy or sell, you have the option of simply letting it expire. Options therefore are the insurance policy of the free market. You negotiate a future price (actually you usually take what you can get if you're an individual investor; the institutional fund managers get to negotiate because they're moving billions around every day), then you pay the other guy up front for the right of refusal later. How much you pay depends on how likely the person giving you this option is to have to make good on it; if your position looks like a sure thing, an option's going to be very expensive (and if it's such a sure thing, you should just make your move on the spot market; it's thus useful to track futures prices to see where the various big players are predicting that your portfolio will move). A put option, which is an option for you to sell something at a future price, is a hedge against loss of value of your portfolio. You can take one out on any single item in your portfolio, or against a portion or even your entire portfolio. If the stock loses value such that the contract price is better than the market price as of the delivery date of the contract, you execute the option; otherwise, you let it expire. A call option, which is an option to buy something at a future price, is a hedge against rising costs. The rough analog is a ""pre-order"" in retail (but more like a ""holding fee""). They're unusual in portfolio management but can be useful when moving money around in more complex ways. Basically, if you need to guarantee that you will not pay more than a certain per-share price to buy something in the future, you buy a call option. If the spot price as of the delivery date is less than the contract price, you buy from the market and ignore the contract, while if prices have soared, you exercise it and get the lower contract price. Stock options, offered as benefits in many companies, are a specific form of call option with very generous terms for whomever holds them. A swaption, basically a put and a call rolled into one, allows you to trade something for something else. Call it the free market's ""exchange policy"". For a price, if a security you currently hold loses value, you can exchange it for something else that you predicted would become more valuable at the same time. One example might be airline stocks and crude oil; when crude spikes, airline stocks generally suffer, and you can take advantage of this, if it happens, with a swaption to sell your airline stocks for crude oil certificates. There are many such closely-related inverse positions in the market, such as between various currencies, between stocks and commodities (gold is inversely related to pretty much everything else), and even straight-up cash-for-bad-debt arrangements (credit-default swaps, which we heard so much about in 2008)."
"First off, the jargon you are looking for is a hedge. A hedge is ""an investment position intended to offset potential losses/gains that may be incurred by a companion investment"" (http://en.wikipedia.org/wiki/Hedge_(finance)) The other answers which point out that put options are frequently used as a hedge are correct. However there are other hedging instruments used by financial professionals to mitigate risk.  For example, suppose you would really prefer that Foo Corporation not go bankrupt -- perhaps because they own you money (because you're a bondholder) or perhaps because you own them (because you're a stockholder), or maybe you have some other reason for wanting Foo Corp to do well. To mitigate the risk of loss due to bankruptcy of Foo Corp you can buy a Credit Default Swap (http://en.wikipedia.org/wiki/Credit_default_swap). A CDS is essentially a bet that pays off if Foo Corp goes bankrupt, just as insurance on your house is a bet that pays off if your house burns down.   Finally, don't ever forget that all insurance is not just a bet that the bad thing you're insuring against is going to happen, it is also a bet that the insurer is going to pay you if that happens.  If the insurer goes bankrupt at the same time as the thing you are insuring goes bad, you're potentially in big trouble." "You're mostly correct, although I think you're missing something essential about no-arbitrage versus an arbitrage argument.  Black-Scholes makes an arbitrage argument, which is that the value of an option should be the same as any portfolio that has identical cash flows, and this is generally a sound argument.  Notice, however, that BS is ultimately an equilibrium model: it tells you the ""correct"" price of an option if the assumptions of BS hold, and doesn't necessarily match observed market prices.  A no-arbitrage condition or model deliberately incorporates observed prices (or yields, or whatever) into the model, so that there cannot be an arbitrage opportunity implied by the model.  This comes up a lot in term structure of interest rate problems, where equilibrium models like Vasicek or Cox-Ingersoll-Ross won't perfectly reproduce the current, observed term structure, and so imply an arbitrage opportunity.  No-arbitrage models like Hull-White specifically match the model's term structure to observed yields/prices, so that there is no arbitrage opportunity between the observed term structure and your model of it.  It's important to note that this will still allow for arbitrage involving bonds that are *not* part of the observed term structure.  As for equivalent martingale measures, you might think about it more generally.  The process involves changing the probability distribution from the actual (which is hard to use for pricing) to a different one that's easier to use but will result in the same prices; this is nearly always a risk-neutral probability.  You can think of equivalent martingale  pricing as asking, ""how would this security behave, and be priced, in a world that is completely risk neutral"", and then making an argument that the prices are in fact equivalent.  EDIT: grammar" You sold a call, and have a risk if the stock rises.  You bought a put and gain when the stock drops. You, sir, have a synthetic short position.  It's Case 3 from your linked example: Suppose you own Long Stock and the company is going to report earnings   but you’re going on vacation. How can you hedge your position without   selling your stock? You can short the stock synthetically with   options! Short Stock = Short Call + Long Put They conclude with the net zero remark, because the premise was an existing long position. A long plus this synthetic short results in a neutral set of positions (and the author's ability to go on vacation not concerned about any movement in the stock.) I don't know why a financial investor or a retail trader would do this. But I can guess why a market maker in options would do this. Let us say you buy an option from an option market maker and the market maker sold the option to you. He made a small profit in the bid-ask spread but now he is holding a short position in the option with unlimited risk exposure. So to protect himself, he will take an offsetting position in the underlying and become delta neutral, so that his position is not affected by the moves in the underlying. In the end, he can do this because he is not in the market to make money by betting on direction, unlike the rest of us poor mortals. He is making money from the bid-ask spread. So to ensure that his profits are not eroded by an adverse move in the underlying, he will continuously seek to be delta neutral. But once again, this is for a market maker. For market takers like us, I still don't understand why we would need to delta hedge. Unfortunately when you deal with options you are going to have to accept some exposure to your greeks. So in your example, you could just buy back month ATM calls. Although delta is going to be pretty static across your portfolio (at least for say the first year, depending on ultima/zomma and other third order greeks) which will keep your lambdas in check, you're still exposed to vega which will ultimately skew lambdas across the board.   Such are the caveats of options - in order to obtain leverage you will need to take a *less* passive outlook, but not by much. A long straddle using equity would be more akin to buying a triple leveraged ETF and an inverse triple leveraged ETF, only because one side will approach zero while the other can theoretically increase to infinity, in a short time span before time decay hits in. The reason your analogy fails is because the delta is 1.0 on both sides of your trade. At the money options, a necessary requirement for a straddle, have a delta of .5 There is an options strategy that uses in the money calls and puts with a delta closer to 1.0 to create an in the money strangle. I'm not sure if it is more similar to your strategy, an analogous options strategy would be better than yours as it would not share the potential for a margin call. I think you need to be very careful here. Covered calls don't reduce risk or increase performance overall. If they did, every investment manager would be using them. In a typical portfolio, over the long term, the gains you give up when your stock goes beyond the strike of your calls will negate the premiums you receive over time. Psychologically, covered calls are appealing because your gains happen over a long period and this is why many people suggest it. But if you believe the Black-Scholes model (used for pricing options) this is what the model predicts over the long term - that you won't do any better than just holding stock (unless you have some edge other traders don't). Now you say you want to reduce diversification and raise your risk. Keeping in mind that there is no free lunch, there are several ways to reduce your risk but they all come at a price. For simplicity, there are three elements to consider - risk, potential gain and cash. These are tradeoffs and you can't simultaneously make them all favorable. You must trade one or more of them to gain in the others. Let's say you wanted to concentrate into a few stocks... how could you counteract the additional risk? 1) Covered calls: very popular strategy usually intended (erroneously) for increasing returns. You get the bonus of cash along with marginally less risk. But you give up a substantial amount of potential return. You won't have blowout returns if you do this. You still face substantial risk. 2) Collar your stock: You sell a covered call while using the cash from the sale to buy puts for protection. You give up potential gains, you're neutral on cash but gain significantly on reducing risk.  3) Use calls as proxy for stock: You don't hold stock but only calls in equivalent delta to the stock you would have held. Substantially lower risk while still having potential gain. Your tradeoff is the cash you have to pay for the calls. When using this, one must be very, very careful not to overleverage.  4) Puts as protection for stocks: This is basically the same as #3 in tradeoffs. You won't overleverage and you also get dividends. But for the most part it's the same. These are the main ways to reduce the risk you gain by concentrating. Options themselves are far broader. But keep in mind that there is no free money. All these techniques involve tradeoffs that you have to be aware of. From Vanguard's Best practices for portfolio rebalancing: Yes, that's the risk. If the stock is bouncing around a lot your options could get assigned.  If it heads south you now are the proud owner of more of a falling stock.  It's good that you're looking to understand the risks of an investment method.  That's important no matter what the method is. You can only lose your 7%. The idea that a certain security is more volatile than others in your portfolio does not mean that you can lose more than the value of the investment. The one exception is that a short position has unlimited downside, but i dont think there are any straight short mutual funds. There are options on options.  Some derivative instruments assets ARE options (some ETFs), and you are able to buy shares of those ETFs OR options on those ETFs.  Secondly, options are just a contract, so you just need to write one up and find someone to buy the contract. The only thing is that the exchange won't facilitate it, so you will have liquidity issues. What you want to do is a diagonal / calendar spread. Buy the back month option, sell the front month option, this isn't a foreign concept and nobody is stopping you.  Since you have extra leverage on your LEAPS, then you just need to change the balancing of your short leg to match the amount of leverage the leaps will provide. (so instead of buying,selling 1:1, you need to buy one leap and perhaps sell 5 puts) Depending on the structure of you're portfolio, it could be that your portfolio is delta neutral to take advantage of diminishing time value on options, short straddles/strangles would be an example. "For diversification against local currency's inflation, you have fundamentally 3 options: Depending on how sure you are on your prediction, and what amount of money you're willing to bet to ""short the country"", you might also consider a mix of approaches from the above. Good luck." On the US markets, most index options are European style.  Most stock and ETF options are, as you noted, American style. In the case of regulated, exchange-traded options, the writer of an options contract is obliged to maintain a margin with their broker, and the broker is obliged to maintain a margin with the clearing house.  (Institutional writers of options will deal directly with the clearing house.) In the event that the writer is unable to make a daily margin call, the broker (or clearing house) may automatically close out (all of) their positions using existing margin held.  If there was a shortfall, the broker (or clearing house) would be left to persue the client (writer) to make good on their obligations. None of this effects the position of the original buyer of the options contract.  Effectively, the buyer's counterparty is their broker's clearing house account.