When speaking of stocks, if an investor has long positions it means that the investor has bought and owns those shares of stocks. By contrast, if  the investor has short positions it means that the investor owes those stocks to someone, but does not actually own them yet. For instance, an investor who owns 100 shares of Tesla (TSLA) stock in his portfolio is said to be long 100 shares. This investor has paid in full the cost of owning the shares.

An investor who has sold 100 shares of TSLA without currently owning those shares is said to be short 100 shares. The short investor owes 100 shares at settlement and must fulfill the obligation by purchasing the shares in the market to deliver. Oftentimes, the short investor borrows the shares from a brokerage firm in a margin account to make the delivery. Then, with hopes the stock price will fall, the investor buys the shares at a lower price to pay back the dealer who loaned them. If the price doesn't fall and keeps going up, the short seller may be subject to a margin call from his broker.

Options Contracts

When an investor uses options contracts in an account, long and short positions have slightly different meanings. Buying or holding a call or put option is a long position because the investor owns the right to buy or sell the security to the writing investor at a specified price. Selling or writing a call or put option is just the opposite and is a short position because the writer is obligated to sell the shares to or buy the shares from the long position holder or buyer of the option. For example, an individual buys (goes long) one Tesla (TSLA) call option from a call writer for $28.70 (the writer is short the call). The strike price on the option is $275 and TSLA currently trades for $303.70 on the market. The writer gets to keep the premium payment of $28.70 but is obligated to sell TSLA at $275 if the buyer decides to exercise the contract at anytime before it expires. The call buyer who is long has the right to buy the shares at $275 at expiration from the writer if the market value of TSLA is greater than $275 + $28.70 = $303.70.

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Explaining a Long and Short Position

Put and call strategies

Long and short positions are used by investors to achieve different results, and oftentimes both long and short positions are established simultaneously by an investor to leverage or produce income on a security. A simple long stock position is bullish and anticipates growth, while a short stock position is bearish. Long call option positions are bullish, as the investor expects the stock price to rise and buys calls with a lower strike price. An investor can hedge his long stock position by creating a long put option position, giving him the right to sell his stock at a guaranteed price. Short call option positions offer a similar strategy to short selling without the need to borrow the stock. This position allows the investor to collect the option premium as income with the possibility of delivering his long stock position at a guaranteed, usually higher, price. Conversely, a short put position gives the investor the possibility of buying the stock at a specified price and he collects the premium while waiting.

These are just a few examples of how combining long and short positions with different securities can create leverage and hedge against losses in a portfolio. It is important to remember that short positions come with higher risks and, due to the nature of certain positions, may be limited in IRAs and other cash accounts. Margin accounts are generally needed for most short positions, and your brokerage firm needs to agree that more risky positions are suitable for you.