Why divide by ask rate to get the spread?
"Mathematically it's arbitrary - you could just as easily use the bid or the midpoint as the denominator, so long as you're consistent when comparing securities.  So there's not a fundamental reason to use the ask.  The best argument I can come up with is that most analysis is done from the buy side, so looking at liquidity costs (meaning how much does the value drop instantaneously purely because of the bid-ask spread) when you buy a security would be more relevant by using the ask (purchase price) as the basis. Meaning, if a stock has a bid-ask range of $95-$100, if you buy the stock at $100 (the ask), you immediately ""lose"" 5% (5/100) of its value since you can only sell it for $95."
The minimum at Schwab to open an IRA is $1000. Why don't you check the two you listed to see what their minimum opening balance is? If you plan to go with ETFs, you want to ask them what their commission is for a minimum trade.  In Is investing in an ETF generally your best option after establishing a Roth IRA? sheegaon points out that for the smaller investor, index mutual funds are cheaper than the ETFs, part due to commission, part the bid/ask spread. "Some investors worry about interest rate risk because they Additional reason is margin trading which is borrowing money to invest in capital markets. Since margin trading includes minimum margin requirements and maintenance margin to protect lender ""such as a broker""  , a decrease in the value of bonds might trigger a threat of a margin call There are other reasons why investors care about interest rate risk  such as spread trade investors who benefit from difference in short term/ long term interest rates. Such investors borrow short term loans -which enables them to pay low interest- and lend long term loans - which enables them to gain high interest-. Any disturbance between the interest rate spread between short term and long term bonds might affect investor's profit and might even lead to losses. In summary , it all depends on you investment objective and financial condition. You should consult with your financial adviser to help plan for your financial goals." Dollar is the lingua franca of the financial industry and unluckily it is the US currency. It is till today considered the most safest investment bet, that is why you have China possesing $3 trillion of US debt, as an investment albiet a very safe one. Financial investors get in queue to by US bonds the moment they are put up for sale. Because of the AAA rating the investors consider it to be safe at a specific rate. Now when you lower the credit rating you are indirectly asking the US government that you want a higher return(yield) on your investments. When you ask for higher yields, it translates into higher interest rates (money US would get for bonds issued decreases and so more bonds are issued). So you basically start looking at a slowdown in consumer spendings households and businesses. With already defaults, repossesions and lesser spending, the slowdown would increase manifold. There are people whose strategy revolves around putting orders at the bid and ask and making money off people who cross the spread.  If you put an order in between the current bid/ask, people running that type of strategy will usually pick it off, viewing it as a discount to the orders that they already have on the bid/ask.  Often these people are trading by computer, so your limit order may get hit so quickly that it appears instantaneous to you.  In reality, you were probably hit by a limit order placed specifically to fill against yours. When you buy a call option, you transfer the risk to the owner of the asset. They are risking losing out on gains that may accumulate in addition to the strike price and paid premium. For example, if you buy a $25 call option on stock XYZ for $1 per contract, then any additional gain above $26 per share of XYZ is missed out on by the owner of the stock and solely benefits the option holder. "This is because volatility is cumulative and with less time there is less cumulative volatility. The time value and option value are tied to the value of the underlying.  The value of the underlying (stock) is quite influenced by volatility, the possible price movement in a given span of time.  Thirty days of volatility has a much broader spread of values than two days, since each day benefits from the possible price change of the prior days.  So if a stock could move up to +/- 1% in a day, then compounded after 5 days it could be +5%, +0%, or -5%.  In other words, this is compounded volatility. Less time means far less volatility, which is geometric and not linear.  Less volatility lowers the value of the underlying.  See Black-Scholes for more technical discussion of this concept. A shorter timeframe until option expiration means there are fewer days of compounded volatility.  So the expected change in the underlying will decrease geometrically.  The odds are good that the price at T-5 days will be close to the price at T-0, much more so than the prices at T-30 or T-90. Additionally, the time value of an American option is the implicit put value (or implicit call).  While an ""American"" option lets you exercise prior to expiry (unlike a ""European"" option, exercised only at expiry), there's an implicit put option in a call (or an implicit call in a put option).  If you have an American call option of 60 days and it goes into the money at 30 days, you could exercise early.  By contract, that stock is yours if you pay for it (or, in a put, you can sell whenever you decide). In some cases, this may make sense (if you want an immediate payoff or you expect this is the best price situation), but you may prefer to watch the price.  If the price moves further, your gain when you use the call may be even better.  If the price goes back out of the money, then you benefited from an implicit put.  It's as though you exercised the option when it went in the money, then sold the stock and got back your cash when the stock went out of the money, even though no actual transaction took place and this is all just implicit. So the time value of an American option includes the implicit option to not use it early.  The value of the implicit option also decreases in a nonlinear fashion, since the value of the implicit option is subject to the same valuation principles. But the larger principle for both is the compounded volatility, which drops geometrically." "Both prices are quotes on a single share of stock. The bid price is what buyers are willing to pay for it. The ask price is what sellers are willing to take for it. If you are selling a stock, you are going to get the bid price, if you are buying a stock you are going to get the ask price. The difference (or ""spread"") goes to the broker/specialist that handles the transaction." Because someone smarter than you by 50 IQ points (a quant) will depart their larger position long before you have a chance to see it coming. Your stop losses are useless as the market will open with the issue below your sell price. Your trade even if place at the same mine would settle after theirs. don't piss in the tall grass with the big dogs. If they are wrong or right does not matter you will be haircut or whipsawed.