Can I use my long position stocks as margin for my short sold stocks?
200% margin for a short sale is outrageous. You should only need to put up 150% margin, of which 50% is your money, and the 100% is the proceeds.  With $100 of your money, you should be able to buy $100 of GOOG and short $100 of PNQI.
I don't see a tag for United States, so I'm having to assume this is US taxes.  It doesn't matter what app you use, IRS trades are all calculated the same. First, you have to report each trade on a 8949 and from that the totals go into a schedule D.  Short term trades are stocks that you've kept exactly one year or less, long term trades are for 1 year + 1 day or more.  Trades where you sold a stock for a loss, then bought that stock back again under 30 days don't get to count as a loss.  This only affects realized capital gains and losses, you don't count fees. First, take all of your short term gains then offset them by all of your short term losses.  Do the same for long term gains and losses.  Short and long term gains are taxed at different rates.  You can deduct losses from short term to your long term and vice versa.  Then you can deduct the total losses up to $3000 (household, $1500 married, filing separately) per year on your regular income taxes or other dividend taxes.  If you have over $3000 in losses, then you need to carry that over to subsequent years. Edited per Dave's comments: thanks Dave "Great question! While investing in individual stocks can be very useful as a learning experience, my opinion is that concentrating an entire portfolio in a few companies' stock is a mistake for most investors, and especially for a novice for several reasons. After all, only a handful of professional investors have ever beaten the market over the long term by picking stocks, so is it really worth trying? If you could, I'd say go work on Wall Street and good luck to you. Diversification For many investors, diversification is an important reason to use an ETF or index fund. If they were to focus on a few sectors or companies, it is more likely that they would have a lop-sided risk profile and might be subject to a larger downside risk potential than the market as a whole, i.e. ""don't put all your eggs in one basket"". Diversification is important because of the nature of compound investing - if you take a significant hit, it will take you a long time to recover because all of your future gains are building off of a smaller base. This is one reason that younger investors often take a larger position in equities, as they have longer to recover from significant market declines. While it is very possible to build a balanced, diversified portfolio from individual stocks, this isn't something I'd recommend for a new investor and would require a substantial college-level understanding of investments, and in any case, this portfolio would have a more discrete efficient frontier than the market as a whole. Lower Volatility Picking individual stocks or sectors would could also significantly increase or decrease the overall volatility of the portfolio relative to the market, especially if the stocks are highly cyclical or correlated to the same market factors. So if they are buying tech stocks, they might see bigger upswings and downswings compared to the market as a whole, or see the opposite effect in the case of utilities. In other words, owning a basket of individual stocks may result in an unintended volatility/beta profile. Lower Trading Costs and Taxes Investors who buy individual stocks tend to trade more in an attempt to beat the market. After accounting for commission fees, transaction costs (bid/ask spread), and taxes, most individual investors get only a fraction of the market average return. One famous academic study finds that investors who trade more trail the stock market more. Trading also tends to incur higher taxes since short term gains (<1 year) are taxed at marginal income tax rates that are higher than long term capital gains. Investors tend to trade due to behavioral failures such as trying to time the market, being overconfident, speculating on stocks instead of long-term investing, following what everyone else is doing, and getting in and out of the market as a result of an emotional reaction to volatility (ie buying when stocks are high/rising and selling when they are low/falling). Investing in index funds can involve minimal fees and discourages behavior that causes investors to incur excessive trading costs. This can make a big difference over the long run as extra costs and taxes compound significantly over time. It's Hard to Beat the Market since Markets are Quite Efficient Another reason to use funds is that it is reasonable to assume that at any point in time, the market does a fairly good job of pricing securities based on all known information. In other words, if a given stock is trading at a low P/E relative to the market, the market as a whole has decided that there is good reason for this valuation. This idea is based on the assumption that there are already so many professional analysts and traders looking for arbitrage opportunities that few such opportunities exist, and where they do exist, persist for only a short time. If you accept this theory generally (obviously, the market is not perfect), there is very little in the way of insight on pricing that the average novice investor could provide given limited knowledge of the markets and only a few hours of research. It might be more likely that opportunities identified by the novice would reflect omissions of relevant information. Trying to make money in this way then becomes a bet that other informed, professional investors are wrong and you are right (options traders, for example). Prices are Unpredictable (Behave Like ""Random"" Walks) If you want to make money as a long-term investor/owner rather than a speculator/trader, than most of the future change in asset prices will be a result of future events and information that is not yet known. Since no one knows how the world will change or who will be tomorrow's winners or losers, much less in 30 years, this is sometimes referred to as a ""random walk."" You can point to fundamental analysis and say ""X company has great free cash flow, so I will invest in them"", but ultimately, the problem with this type of analysis is that everyone else has already done it too. For example, Warren Buffett famously already knows the price at which he'd buy every company he's interested in buying. When everyone else can do the same analysis as you, the price already reflects the market's take on that public information (Efficent Market theory), and what is left is the unknown (I wouldn't use the term ""random""). Overall, I think there is simply a very large potential for an individual investor to make a few mistakes with individual stocks over 20+ years that will really cost a lot, and I think most investors want a balance of risk and return versus the largest possible return, and don't have an interest in developing a professional knowledge of stocks. I think a better strategy for most investors is to share in the future profits of companies buy holding a well-diversified portfolio for the long term and to avoid making a large number of decisions about which stocks to own." "Simplest way to answer this is that on margin, one is using borrowed assets and thus there are strings that come with doing that. Thus, if the amount of equity left gets too low, the broker has a legal obligation to close the position which can be selling purchased shares or buying back borrowed shares depending on if this is a long or short position respectively. Investopedia has an example that they walk through as the call is where you are asked to either put in more money to the account or the position may be closed because the broker wants their money back. What is Maintenance Margin? A maintenance margin is the required   amount of securities an investor must hold in his account if he either   purchases shares on margin, or if he sells shares short. If an   investor's margin balance falls below the set maintenance margin, the   investor would then need to contribute additional funds to the account   or liquidate stocks in the account to bring the account back to the   initial margin requirement. This request is known as a margin call. As discussed previously, the Federal Reserve Board sets the initial   margin requirement (currently at 50%). The Federal Reserve Board also   sets the maintenance margin. The maintenance margin, the amount of   equity an investor needs to hold in his account if he buys stock on   margin or sells shares short, is 25%. Keep in mind, however, that this   25% level is the minimum level set, brokerage firms can increase, but   not decrease this level as they desire. Example: Determining when a margin call would occur. Assume that an   investor had purchased 500 shares of Newco's stock. The shares were   trading at $50 when the transaction was executed. The initial margin   requirement on the account was 70% and the maintenance margin is 30%.   Assume no transaction costs. Determine the price at which the investor   will receive a margin call. Answer: Calculate the price as follows: $50 (1- 0.70) = $21.43 1 - 0.30 A margin call would be received when the price of Newco's stock fell   below $21.43 per share. At that time, the investor would either need   to deposit additional funds or liquidate shares to satisfy the initial   margin requirement. Most people don't want ""Margin Calls"" but stocks may move in unexpected ways and this is where there are mechanisms to limit losses, especially for the brokerage firm that wants to make as much money as possible. Cancel what trade? No, the broker will close the position if the requirement isn't kept. Basically think of this as a way for the broker to get their money back if necessary while following federal rules. This would be selling in a long position or buying in a short sale situation. The Margin Investor walks through an example where an e-mail would be sent and if the requirement isn't met then the position gets exited as per the law." "Below is just a little information on short selling from my small unique book ""The small stock trader"":  Short selling is an advanced stock trading tool with unique risks and rewards. It is primarily a short-term trading strategy of a technical nature, mostly done by small stock traders, market makers, and hedge funds. Most small stock traders mainly use short selling as a short-term speculation tool when they feel the stock price is a bit overvalued. Most long-term short positions are taken by fundamental-oriented long/short equity hedge funds that have identified some major weaknesses in the company. There a few things you should consider before shorting stocks: Despite all the mystique and blame surrounding short selling, especially during bear markets, I personally think regular short selling, not naked short selling, has a more positive impact on the stock market, as: Lastly, small stock traders should not expect to make significant profits by short selling, as even most of the great stock traders (Jesse Livermore, Bernard Baruch, Gerald Loeb, Nicolas Darvas, William O’Neil, and Steven Cohen,) have hardly made significant money from their shorts. it is safe to say that odds are stacked against short sellers. Over the last century or so, Western large caps have returned an annual average of between 8 and 10 percent while the returns of small caps have been slightly higher.  I hope the above little information from my small unique book was a little helpful! Mika (author of ""The small stock trader"")" "I think to some extent you may be confusing the terms margin and leverage. From Investopedia Two concepts that are important to traders are margin and leverage. Margin is a loan extended by your broker that allows you to leverage the funds and securities in your account to enter larger trades. In order to use margin, you must open and be approved for a margin account. The loan is collateralized by the securities and cash in your margin account. The borrowed money doesn't come free, however; it has to be paid back with interest. If you are a day trader or scalper this may not be a concern; but if you are a swing trader, you can expect to pay between 5 and 10% interest on the borrowed money, or margin. Going hand-in-hand with margin is leverage; you use margin to create leverage. Leverage is the increased buying power that is available to margin account holders.  Essentially, leverage allows you to pay less than full price for a trade, giving you the ability to enter larger positions than would be possible with your account funds alone. Leverage is expressed as a ratio. A 2:1 leverage, for example, means that you would be able to hold a position that is twice the value of your trading account. If you had $25,000 in your trading account with 2:1 leverage, you would be able to purchase $50,000 worth of stock. Margin refers to essentially buying with borrowed money.  This must be paid back, with interest.  You also may have a ""margin call"" forcing you to liquidate assets if you go beyond your margin limits. Leverage can be achieved in a number of ways when investing, one of which is investing with a margin account." hmmm. I think it's because in both cases, you must pay for it up front, before the positions are closed out. You own nothing except the right to buy the stock re: the call, and the obligation to buy the stock re: the short.  You buy a call, but must borrow the stock, for which you must put some margin collateral and there is a cost to borrow. You pay for that, of course.  I wouldn't call it lending though. No, CFD is not viable as a long term trading strategy.  You have a minimum margin to maintain, and you are given X days to top up your margin should you not meet the margin requirements. Failure to meet margin requirements will result in a forced sell where you are no longer able to hold onto the stock. A long term trading strategy is where you hold onto the stock through the bad times of the company and keep it long enough to see the good times. However, with CFD, you may be forced to sell before you see the good times. In addition, you incur additional lending charges (e.g. 4%-6%) for the ability to leverage. You would generally have to pay interest for everyday you hold the position overnight.  If you never close the position and the stock price goes to zero, you will be closed out and credited with your profit. If you never close the position and the stock price keeps going up and up, your potential loss is an unlimited amount of money.  Of course your broker may close you out early for a number of reasons, particularly if your loss goes above the amount of capital you have in your trading account.