What kind of symbol can be shorted?
Any publicly traded financial instrument can be sold short, in theory.  There are, however, many regulations associated with short sales of US equities that may prevent certain stocks from being sold short at certain times or through certain brokers. Some examples: the most basic requirement (this isn't a regulation, it's just the definition of a short sale) is that you or your broker must have access to someone willing to loan you his/her shares.  If you are interested in shorting a security with few shares outstanding or low trade volume, there may simply not be enough people in the world willing to loan you theirs.  Alternatively, there may be a shareholder willing to loan shares, but your broker may not have a relationship with the clearing house that shareholder is using.  A larger/better/different broker might be able to help. threshold securities list - since 2005, each day certain securities are not allowed to be sold short based on their recent history of liquidity.  Basically, if a certain number of transactions in a security have not been correctly settled over the past few days, then the SEC has reason to believe that short sales (which require extra transactions) are at higher risk of falling through. circuit breaker a.k.a. alternative uptick - since 2011, during certain market conditions, exchanges are now required to reject short sales for certain securities in order to prevent market crashes/market abuse. Some platforms/brokers have HTB indication for a stock symbol, meaning Hard To Borrow. That usually means you can't sell it short at the moment.
In addition to the higher risk as pointed out by @JamesRoth, you also need to consider that there are regulations against 'naked shorting' so you generally need to either own the security, or have someone that is willing to 'loan' the security to you in order to sell short.  If you own a stock you are shorting, the IRS could view the transaction as a Sell followed by a buy taking place in a less than 30 day period and you could be subject to wash-sale rules.  This added complexity (most often the finding of someone to loan you the security you are shorting) is another reason such trades are considered more advanced. You should also be aware that there are currently a number of proposals to re-instate the 'uptick rule' or some circuit-breaker variant. Designed to prevent short-sellers from driving down the price of a stock (and conducting 'bear raids etc) the first requires that a stock trade at the same or higher price as prior trades before you can submit a short.  In the latter shorting would be prohibited after a stock price had fallen a given percentage in a given amount of time.  In either case, should such a rule be (re)established then you could face limitations attempting to execute a short which you would not need to worry about doing simple buys or sells.   As to vehicles that would do this kind of thing (if you are convinced we are in a bear market and willing to take the risk) there are a number of ETF's classified as 'Inverse Exchange Traded Funds (ETF's) for a variety of markets that via various means seek to deliver a return similar to that of 'shorting the market' in question.  One such example for a common broad market is ticker SH the ProShares Short S&P500 ETF, which seeks to deliver a return that is the inverse of the S&P500 (and as would be predicted based on the roughly +15% performance of the S&P500 over the last 12 months, SH is down roughly -15% over the same period).  The Wikipedia article on inverse ETF's lists a number of other such funds covering various markets.   I think it should be noted that using such a vehicle is a pretty 'aggressive bet' to take in reaction to the belief that a bear market is imminent.  A more conservative approach would be to simply take money out of the market and place it in something like CD's or Treasury instruments.  In that case, you preserve your capital, regardless of what happens in the market. Using an inverse ETF OTOH means that if the market went bull instead of bear, you would lose money instead of merely holding your position. I would say that, for the most part, money should not be invested in the stock market or real estate.  Mostly this money should be kept in savings: I feel like your emergency fund is light.  You do not indicate what your expenses are per month, but unless you can live off of 1K/month, that is pretty low.  I would bump that to about 15K, but that really depends upon your expenses. You may want to go higher when you consider your real estate investments.  What happens if a water heater needs replacement?  (41K left) EDIT:  As stated you could reduce your expenses, in an emergency, to 2K.  At the bare minimum your emergency fund should be 12K.  I'd still be likely to have more as you don't have any money in sinking funds or designated savings and the real estate leaves you a bit exposed.  In your shoes, I'd have 12K as a general emergency fund.  Another 5K in a car fund (I don't mind driving a 5,000 car), 5k in a real estate/home repair fund, and save about 400 per month for yearly insurance and tax costs.  Your first point is incorrect, you do have debt in the form of a car lease.  That car needs to be replaced, and you might want to upgrade the other car.  How much?  Perhaps spend 12K on each and sell the existing car for 2K?  (19K left). Congratulations on attempting to bootstrap a software company.  What kind of cash do you anticipate needing?  How about keeping 10K designated for that?  (9K left) Assuming that medical school will run you about 50K per year for 4 years how do you propose to pay for it?  Assuming that you put away 4K per month for 24 months and have 9K, you will come up about 95K short assuming some interests in your favor.  The time frame is too short to invest it, so you are stuck with crappy bank rates. "A company whose stock is available for sale to the public is called a publicly-held or publicly-traded company.  A public company's stock is sold on a stock exchange, and anyone with money can buy shares through a stock broker. This contrasts with a privately-held company, in which the shares are not traded on a stock exchange. In order to invest in a private company, you would need to talk directly to the current owners of the company. Finding out if a company is public or private is fairly easy.  One way to check this is to look at the Wikipedia page for the company.  For example, if you take a look at the Apple page, on the right sidebar you'll see ""Type: Public"", followed by the stock exchange ticker symbol ""AAPL"".  Compare this to the page for Mars, Inc.; on that page, you'll see ""Type: Private"", and no stock ticker symbol listed. Another way to tell: If you can find a quote for a share price on a financial site (such as Google Finance or Yahoo Finance), you can buy the stock.  You won't find a stock price for Mars, Inc. anywhere, because the stock is not publicly traded." "Because an equity option can be constructed at essentially any price by two willing counterparties on an exchange, there are not enough ISINs to represent the entire (i.e. infinite) option chain for even a single stock on a single expiration date.  As a result, ISINs are not generated for each individual possible options contract.  Instead the ISIN is used only to refer to the ""underlying"" symbol, and a separate formula is used to refer to the specific option contract for that symbol: So that code you pasted is not an ISIN but rather the standard US equity option naming scheme that you need to provide in addition to the ISIN when talking to your broker. Note that ISINs and formulas for referring to option contracts in other countries can behave quite differently.  Also, there are many countries and markets that don't need ISINs because the products in question only exist on a single exchange.  In those cases the exchange is pretty much free to make up whatever ID scheme it wants. P.S. Now I'm curious how option chains are identified for strike prices above $99,999.  I looked up the only stock I can think of that trades above that price (BRK.A), but it doesn't seem to have an option chain (or at least Google doesn't show it) ..." 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'report an error')" "I'd personally display ""n/a"" The only other answer that makes sense to me other is ""infinity"" (phone keyboard doesn't allow me to input the symbol). This would at least allow you to show direction by using positive and negative  infinity and mathematical as the the initial value approaches zero the percentage change approaches infinity which is the closet you can get to a meaningful value" Shorts are difficult because you have to find someone to lend the stock to you. In contrast, put options don't require that. They also have some nice properties like you're only out the contract price. The options chain for BSFT will give you an idea of where the market is.  Keep in mind that BSFT only IPO'd last year and announced blowout earnings recently. Make sure the P:E you're looking at is using recent earnings reports! "Diversify into leveraged short/bear ETFs and then you can quit your job and yell at your boss ""F you I'm short your house!"" edit: this is a quote from Greg Lippmann and mentioned in the book ""The Big Short"""