Trading and valuing bonds

Trading and valuing bonds
See also: Bond valuation
The interest rate that the issuer of a bond must pay is influenced by a variety of factors, such as current market interest rates, the length of the term and the creditworthiness of the issuer.

These factors are likely to change over time, so the market price of a bond will vary after it is issued. This price is expressed as a percentage of nominal value. Bonds are not necessarily issued at par (100% of face value, corresponding to a price of 100), but bond prices converge to par when they approach maturity (if the market expects the maturity payment to be made in full and on time) as this is the price the issuer will pay to redeem the bond. At other times, prices can be above par (bond is priced at greater than 100), which is called trading at a premium, or below par (bond is priced at less than 100), which is called trading at a discount. Most government bonds are denominated in units of $1000, if in the United States, or in units of £100, if in the United Kingdom. Hence, a deep discount US bond, selling at a price of 75.26, indicates a selling price of $752.60 per bond sold. (Often, in the US, bond prices are quoted in points and thirty-seconds of a point, rather than in decimal form.) Some short-term bonds, such as the U.S. Treasury Bill, are always issued at a discount, and pay par amount at maturity rather than paying coupons. This is called a discount bond.

The market price of a bond is the present value of all expected future interest and principal payments of the bond discounted at the bond's redemption yield, or rate of return. That relationship defines the redemption yield on the bond, which represents the current market interest rate for bonds with similar characteristics. The yield and price of a bond are inversely related so that when market interest rates rise, bond prices fall and vice versa. Thus the redemption yield could be considered to be made up of two parts: the current yield (see below) and the expected capital gain or loss: roughly the current yield plus the capital gain (negative for loss) per year until redemption.

The market price of a bond may include the accrued interest since the last coupon date. (Some bond markets include accrued interest in the trading price and others add it on explicitly after trading.) The price including accrued interest is known as the "full" or "dirty price". (See also Accrual bond.) The price excluding accrued interest is known as the "flat" or "clean price".

The interest rate adjusted for (divided by) the current price of the bond is called the current yield (this is the nominal yield multiplied by the par value and divided by the price).

The relationship between yield and maturity for otherwise identical bonds is called a yield curve.

Bonds markets, unlike stock or share markets, often do not have a centralized exchange or trading system. Rather, in most developed bond markets such as the U.S., Japan and western Europe, bonds trade in decentralized, dealer-based over-the-counter markets. In such a market, market liquidity is provided by dealers and other market participants committing risk capital to trading activity. In the bond market, when an investor buys or sells a bond, the counterparty to the trade is almost always a bank or securities firm acting as a dealer. In some cases, when a dealer buys a bond from an investor, the dealer carries the bond "in inventory." The dealer's position is then subject to risks of price fluctuation. In other cases, the dealer immediately resells the bond to another investor.

Bond markets can also differ from stock markets in that, in some markets, investors sometimes do not pay brokerage commissions to dealers with whom they buy or sell bonds. Rather, the dealers earn revenue by means of the spread, or difference, between the price at which the dealer buys a bond from one investor -- the "bid" price -- and the price at which he or she sells the same bond to another investor--the "ask" or "offer" price. The bid/offer spread represents the total transaction cost associated with transferring a bond from one investor to another.