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Nihonjin1051 I changed my mind, looking at my schedule, it's better to get this done now. NB I am not a professional trader (different department, so to speak), so I am approaching this from a non-professional perspective, and perhaps @
Peter C might be a better source of more technical information if you're interested (or he can correct mistakes I make below). I will speak simplistically here, as it's fairly easy to find technical details through Google if you want to get heavier on the math, the regulatory requirements (e.g. the specific levels of maintenance margin for various instruments), what credit analysts look at to determine creditworthiness (e.g. debt coverage ratios, debt to total enterprise value, etc.), or other details.
First, we need to define volatility. There are two common ways of defining volatility: one is the simple mathematical calculation of the standard deviation in price changes over a defined period of time (historical volatility), and the second is the volatility index, referred to as VIX for the S&P 500-related measure, but also exists for each that is optionable (implied volatility). VIX is a bit more complicated, since its value is derived from options pricing, specifically using a formula to derive expected volatility by averaging the weighted prices of out-of-the-money puts and calls. Again, I'm not sure if you're familiar with options, but the short and simple version is that options are the right to buy or sell an instrument at specific price (called a strike price) within a certain time frame. This "right to buy or sell" can itself be priced based on how far the underlying instrument is trading from the strike price, how much time is left in the contract, how volatile the underlying instrument is, and a few other factors.
The first definition of volatility dictates that when the standard deviation of price changes increases, volatility by definition is increased. For example, if a stock moves by 1% a day for a while, and then all of a sudden moves by 3% a day (up or down), it can be said that its volatility has increased. This could be due to stock-specific reasons (i.e. news, thin trading volume in the stock, etc.) or could be due to general market conditions (everyone is looking to dump stocks, any stocks, because of poor market conditions).
The second definition of volatility is a function of trading activity in the options, as I described. For this reason, if we talk about VIX when describing volatility, then volatility doesn't necessarily increase when the market drops, because the players trading the stocks may have expectations that the market will rebound, and thus do not bid up the price of puts. On the other hand, VIX can also rise when the market is rising, if the players involved are heavily buying puts (and thus bidding up the price) to hedge their positions. If you want the mathematical details, please see the CBOE site's primer on the VIX (
CBOE Futures Exchange - Education ). That said, VIX does tend to spike in response to "fear" in the market (the market drops, traders buy puts to protect themselves), and it tends to subside in bull markets.
OK, that intro out of the way, how is leverage involved? First, options themselves are leverage. To steal from Investopedia:
"Leverage can be created through options, futures, margin and other financial instruments. For example, say you have $1,000 to invest. This amount could be invested in 10 shares of Microsoft stock, but to increase leverage, you could invest the $1,000 in five options contracts. You would then control 500 shares instead of just 10." Futures instruments are also a form of leverage, where a smaller amount of required cash in the account (called maintenance margin) can control an instrument worth multiples of the maintenance margin.
The second form of leverage is margin debt, where traders borrow money to invest in instruments. For retail traders, if you have $100,000 to invest, you can borrow another $100,000 from your broker, and trade with $200,000. Of course, if the value of your investment declines too much, you will get a "margin call," where the broker asks for an immediate cash injection to maintain your position, or otherwise the broker will forcibly liquidate your position to reclaim the cash it lent to you. You can see how in a market that moves against your position, this can lead to a cascade effect. For example, if you are long a stock, and the stock declines, you may get a margin call, and be forced to sell your stock, which causes the stock to decline further. Writ large across multiple players, you can see how this could quickly effect the broad market. Events can cause sharp changes in the market (e.g. the failure of Lehman Brothers, the announcement of QEx, etc.) which can catch people out on the wrong side of a trade, and as they scramble to close their positions, it causes volatility to increase.
The third form of leverage is corporate debt. Corporations borrow money from banks and sell bonds to investors in order to raise money to fund their operations, and occasionally, in order to pay out dividends to shareholders. Debt isn't free, and requires cash flow to cover the interest payments, and sufficient cash to pay off the principal when the debt is due (or roll over the debt into a new bond). When the economy is doing well, debt is cheap, and cash flow tends to be strong, so corporations can easily pay the interest. When the economy starts doing poorly, capital becomes more scarce, and the cost of debt (i.e. interest) rises, and cash flow weakens, so the interest on the debt is harder to pay. When companies get into trouble, they default on their debt, which causes losses to investors, who in turn may be forced to sell other instruments to raise enough cash to maintain their own capital requirements--so you can see the cascade effect there, as well. Of course, this cascade of debt defaults also strangles the real economy, as investors demand higher interest rates precisely when companies need capital the most. Since the debt markets generally follow the business cycle, corporate leverage also rises and falls on a cyclical basis.
Sorry, out of time, I have to end it here. Hopefully that gets you started for further research, if you are interested.