Why accretion matters
Accretion separates the return created by the pull to par from coupon income and market price movement. It affects reported income, book value, tax treatment, and comparisons between discount and par bonds.
How it is applied
Investors may apply a straight-line or effective-interest method, depending on accounting and tax rules. Under effective interest, the periodic yield is applied to opening carrying value, then cash coupon is deducted to find the discount accreted. For a discount bond, accretion can be modeled by increasing carrying value toward par under the effective-interest method. The periodic interest income equals the opening carrying value multiplied by the effective yield; cash coupon received is then subtracted to obtain the increase in carrying value.
Portfolio example
A bond bought for $920 is expected to repay $1,000 in four years. Part of the $80 discount is recognized during each period, increasing carrying value even if its quoted market price does not change. Consider a bond purchased for 960 that will repay 1,000 and pays a coupon below its effective yield. If effective-interest income for the first period is 48 and the cash coupon is 40, carrying value accretes by 8 to 968. The process repeats using the new carrying value, so the balance approaches 1,000 at maturity.
How to interpret it
Accretion can raise accounting income without producing immediate cash. For a performing bond held to maturity, carrying value generally converges toward redemption value. Faster accretion does not by itself mean a better investment. Accretion can raise reported interest income without producing equivalent current cash. Analysts should distinguish this accounting recognition from cash yield and from a change in the issuer’s credit quality. In merger analysis, an accretive transaction increases a selected per-share measure, usually earnings per share, but does not automatically create economic value.
Limitations and common misconceptions
Default, calls, sales before maturity, changing cash-flow estimates, and tax rules can prevent the expected pull to par. Accounting accretion is not the same as an observable market gain and should not be treated as guaranteed return. The term has different applications in fixed income, accounting, and corporate transactions. Bond accretion depends on purchase price, expected cash flows, yield assumptions, prepayments, and impairment rules. Earnings accretion can be engineered with cheap financing or share repurchases and may ignore integration costs, risk, or return on invested capital. The relevant method and assumptions should always be stated.
Sources and further reading
- Fixed-Income Securities: Defining ElementsCFA Institute
- Fixed-Income Bond Valuation: Prices and YieldsCFA Institute
- BondsFINRA