Effective Duration

Categories: Bonds

When you buy a bond, it will have a duration. Bonds are like loans, and the duration represents the amount of time it takes to pay the money back.

So you might purchase a bond with a 5% interest rate and a duration of five years. That means you'll get a 5% return per year for each of the next five years. At the end of five years, the money is paid back and the bond expires.

Some bonds have a clause that lets them get retired early. It's like a parachute for the bond issuer. If they don't need the money anymore, or think they can get a better deal somewhere else, they can "call" the bond, basically buying it back at a set price.

Effective duration measures how this option impacts the price for callable bonds.

You buy a bond with a 10-year duration. But if it's callable after three years, you might not get to hold it for the full decade.

That circumstance is bad for you, because it means you won't get those sweet interest payments for as long. If you've got your 10-year bond and it gets called after four years, that's six years of interest you missed out on.
Because of these factors, the price of the callable bond is heavily impacted by movements in interest rates. If prevailing rates are sitting at 7% and you have a bond paying out at 5%, it's not going to get called. The company has a pretty good deal. If it were to call the bond and issue a new set, instead of paying 5%, it would have to pay 7%. Calling would be a mistake.

But say interest rates plunge to 4%. It might be worth it to call in the 5% bonds and issue a new set paying out 4%. The company would save money with the lower interest rate. It just becomes a question of whether it would be worth the effort.

Effective duration is a mathematical equation that takes all this into account, using the callable bond interest rate and current prevailing rates to describe the impact on the bond's price.

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Finance: How does duration affect bonds ...2 Views

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And finance Allah Shmoop How does duration affect bonds Okay

00:09

people It's a tale of two bond babies They're both

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incubating in this well giant bond Womb Meet Harry Harry

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the homunculus He's a bond He's almost ready to come

00:20

out and say hey to the world He'll turn right

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into cash when he you know exits He carries in

00:25

his heart a short term bond with life We know

00:29

a ton about him We could see his excellent facial

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features here in his strong arms here and his you

00:35

know excellent job They're incubating Harry Well Harry is a

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short term bond We have only a very short period

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of time until he matures and then is on his

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own at least not directly You know swimming in our

00:46

bond Cool little ambiguity with tons of doctors looking in

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on him Little risk that his AIPO are rather retirement

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from incubating doesn't go well Short term bond Short duration

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until maturity Not very volatile because well we can see

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so much already and have clarity that he's healthy Like

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the payments supporting him are right there We can identify

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him No risk no worries Bond pays off And everyone

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moves on Now Meet Justin fertilized a tiny dot ages

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until he's born or matures We have no idea what

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he'll look like how he'll perform in the incubation process

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whether the womb will continue to be a healthy pool

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to swim in or well frankly whether or not he'll

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even make it Justin is a long term bond or

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a bond with long duration like when a given company

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sells one hundred million dollars worth of their bonds promising

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to pay five percent a year in interest and then

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pay back the principal in thirty years That's a long

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bond Thirty years from now is eternity For a lot

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of companies we'll think about what the world looked like

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thirty years ago Yahoo was just coming into prominence Is

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one of the largest companies in the world Well guess

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what it died Nokia not Apple was the largest market

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cap company in the world or most highly valued company

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in the world It died Facebook and Google really weren't

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even formed so long Duration bonds have extreme sensitivity to

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very small inputs Early in there Jess Station Disney has

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a hundred year bond Siri's that are about two decades

02:15

into their maturity Is there no risk that Disney will

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be gone in eighty years Like Well could ABC Television

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no longer exist because producers just stream their own TV

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shows on the Web and they don't need a network

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Is it possible ESPN is gone Because the NFL and

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others just want to go direct to customers They don't

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need ESPN anymore Could roaming gangs have taken over Disneyland

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and Disney World and the other Disney thing He's making

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it you know not the happiest place on Earth You

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know like the Pirates of the Caribbean weren't menacing enough

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So it's not like one in a million shot that

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Disney joins Yahoo in Nokia in the next eighty years

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When bonds have long durations tons of exogenous risk I

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risk you can't imagine fathom believe or accept comes into

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play And one other big element hits long duration bonds

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Very hard That is prevailing interest rates like let's imagine

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that when Justin was you know planted the world's economies

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were fragile needing a boost from low interest rates Teo

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Turbo charge things and help get the world's economies going

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again So at that time for say a rated you

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know best quality bond paper Well rates were four percent

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But then a dozen years later inflation in a globally

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heated mesh of economies started to be a real thing

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and central banks around the world began raising rates So

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twelve years later that prevailing rate was seven percent instead

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of four And Justin was yielding just four Like his

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yield doesn't change year after year or rather his coupon

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or that four percent he's paying doesn't change Year after

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year the price of the bond might go down and

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it does so now for eighteen freaking more years until

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that thirty year maturity bond of just and matures and

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then pays cash well Justin will be paying three percent

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per year less than his brethren who are being seven

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percent essentially costing his parental investors in him One point

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Oh three to the eighteenth power there That's how we

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do the bond math on how much that cost them

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Or set another way Investors in a seven percent yield

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ER versus the four percent or in Justin would get

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almost seventy percent more money by the time Justin pops

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out of the oven then sticking with Justin So think

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about this in extreme short case situations like let's say

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you have Harry and Justin both yielding four percent Harry

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is doing a year Justin is due in thirty years

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If tomorrow rates suddenly jumped to seven percent overnight well

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then Harry loses one year's worth of opportunity Cost meaning

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Harry only yields four percent instead of the prevailing seven

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percent right Yeah he could have been a seven percent

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or he could have been somebody instead of a bum

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So Harry loses three percent for one year Not great

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but not a disaster either So if that rate hike

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suddenly happened well what would Harry likely trade at one

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year before his cash conversion in principle payoff Well if

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Harry was a thousand dollar bond and he'd pay forty

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bucks over that year the four percent there But the

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new rates were paying seventy bucks over that year Wealth

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Then you'd ask How does Harry's forty dollars in interest

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payments and just so that they now pay seventy dollars

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or set another way and ignoring some time value of

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money things here for simplicity If Harry dropped in price

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to nine hundred seventy dollars well then in the course

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of a year He'd appreciate thirty bucks for the principal

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while still paying the forty and interest And he deliver

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seventy bucks in total return like thirty and appreciation in

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forty and interest to his parental investors and match the

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seven percent prevailing rates Okay so that's Harry in one

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year What happens to just think about it He's got

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only four percent a year yield That's got to adjust

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to the new world reality of seven percent a year

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RO rates that kind of class of a bond Well

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his thousand dollars par value That market price drops a

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lot In fact it dropped by one point Oh three

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to the eighteenth power Or rather that becomes the denominator

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in the new calculation So the thousand dollar bond value

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drops to a thousand invited by one point seven ish

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or about five hundred eighty five dollars and then slowly

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slowly slowly over eighteen years It then crawls back tto

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par assuming the parent company that issued Justin Will survives

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the entire time And then finally mercifully eighteen years later

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the emerges at par as a Philadelphia On paying off

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in cash he goes out into the rial adult bond

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world and it does you no adult bond things But

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hopefully he makes good decisions and doesn't get too heavily 00:06:37.933 --> [endTime] into you know bondage Oh my

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