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When machines take over markets | R L Shankar | TEDxGLIMChennai


let’s start with a quick show of hands

how many of you here like taking

afternoon naps good god I’m in so much

trouble today I mean not about tell

o’clock all right the benefits of these

naps are well documented let me add a

little known benefit to this list assume

you are a u.s. investor who regularly

takes afternoon naps the chances of you

getting a cardiac arrest on the sixth

May of 2010 would have been

significantly lower than somebody who

doesn’t takes these naps sounds

interesting right here is why 6 May 2010

began like any other normal trading day

in the US markets market us up a bit

down a bit nothing much that we hadn’t

seen before so let’s say you took your

beauty nap at 2:30 p.m. and then woke up

at 3:30 p.m. right what happened to the

market the market didn’t do much right

so there’s nothing much to worry about

however if we had stayed awake during

this period this is what you would have

witnessed around 2:30 p.m. the markets

crashed dramatically the Dow Jones index

which is a proxy for the financial

health of the stock markets fell by a

massive 9.6 percentage as a result over

1 trillion dollars of investors wealth

was wiped out let’s put that number in

perspective right one trillion dollars

is twice the combined size of Singapore

and Hong Kong twice the combined size of

Singapore and Hong Kong economy was

wiped out within 15 minutes you should

have definitely taken that nap right

however if that sounded strange what

came next was even stranger but the next

15 minutes the market recovered and went

back to where it was earlier as if

nothing had happened right this crash is

referred to as a flash crash there’s

been six years since a crash happened

during the past six years we have

learned a lot not a lot about this crash

these learnings have in turn

fundamentally enhanced our understanding

of the financial markets

these learnings are by no means specific

to the US market

some of them apply even to the Indian

market where we are assembled today so

it is some of these insights that I

would like to share now let’s start with

a simple thought experiment right I’ll

give that you are sitting in a bar

that’s a good place to visualize

yourself in right now right so you

you’ve got a nice window conifer gonna

see for yourself after some time you see

your friend stepping out hey woody be

ten steps later oh let’s say fifteen

steps later of course it depends on the

amount of alcohol is consumed right

let’s assume that is consumed a lot of

alcohol

it’s going to be absolutely difficult to

predict where he would be ten steps

later right this part is often referred

to as a drunkard walk or in statistics

terms a random walk

many believe that stock prices are like

drunkard it’s very difficult to predict

their future prices so what is it that

we can predict let’s revisit the bar

right so now after stepping out the

drunkard our friend unchanged his dog

and they both start walking like before

it is very difficult to predict where

our friend would be but there is

something else that we can predict with

a lot of confidence right the distance

between the dog and the Drunken assuming

the drunkard did not treat the dog badly

the dog will always stay close to that

drunkard no matter where he won this off

stock market is full of dogs and

drunkards not literally of course right

what do I mean by this

now let’s say we have two stocks Google

and poodle poodle stands for a poor

man’s Google something that I made up

right so don’t look for it and Bloomberg

or something like that

so the key assumption here is that both

of them belong to the same sector have

similar business models and hence their

prices are driven by similar factors not

surprisingly they prices track each

other now let’s assume that over the

next two periods the price of poodle

falls while that of Google remains

stagnant the prisoners

what is likely to happen in the next

period before we make the call because

obviously scan use outlets for any

information relevant to poodle let’s say

we do not find any news or information

that would justify this dramatic crash

in price of poodle perhaps is just a

temporary aberration and eventually the

prices would converge what you’re

essentially betting here is that the

Google and poodle or the dog and

drunkard which eventually converge this

is what is referred to as space trading

as we are not looking at stocks in

isolation but in groups off took let’s

make it a bit more realistic right if

all of that I am doing is tracking these

two stocks I’m gonna spend a lot of time

praying that they would eventually

diverge because unless they diverge I

don’t have a trading opportunity right

however if I were to track three stocks

I can now work with three pairs if I

were to track hundred stocks symbol

algebra tells us that it can work with

close to 5,000 pairs my opportunity said

immediately explodes

however with great opportunities come

great pain it’s almost impossible for

the human brain to simultaneously

process information about 5,000 pairs

this is where algorithms step in and

algorithm is nothing but a series of

instructions to a computer right it’s

relatively straightforward to ask the

computer do the to the following read

prices of various stocks identify the

pairs that are moving away from each

other

and for the ones that have really moved

far away from each other place bets that

they will eventually converge this is

referred to as algorithmic trading a

practice where algorithms scan the

market identify opportunities and

execute trades all with no human

intervention right so it’s very

important to clarify that pace trading

is not the only algorithmic trading

strategy right now let’s make this

a bit more interesting now right let’s

add a bit more color what will happen if

I were to put these algorithms on drugs

or hallucinogens right what I get is

what is referred to as high-frequency

trading something that I’m going to talk

about now let me start with a very

simple illustration in US stocks are

primarily traded in New York and New

Jersey

however contracts that are tightly

linked to these stocks are traded in

Chicago these contracts could be simple

bets on whether the price is going to go

up or down given their tight linkages

it’s natural that the prices will move

together and hence they form the ideal

dog and drunkard pick an algorithm that

can continuously monitor the prices at

these two locations will be able to

exploit any temporary divergence in

prices by some estimates if a trading

firm can capture the monopoly of

exploiting these prices it stands to

make about twenty billion dollars in

annual profit that’s twenty billion

dollars in annual profit but how can a

firm capture this monopoly right

everything else remaining constant the

firm that is able to communicate the

fastest with these two exchanges will

have the upper hand it’s been surprising

that this has triggered a new kind of

arms race a race for higher and higher

speed training that happens at

exceptionally high speeds is referred to

as high frequency trading in 2012

Financial Times published a report by by

they said that hey cities account for 84

percentage of trading in u.s. stock

markets 84 percentage really investors

suggest pension funds mutual funds hedge

funds brokerage and other institutional

investors accounted for a mere 16

percentage it’s very tempting to

identify such prolific growth only with

Western markets like us the Indian

market where algorithmic trading was

introduced in the year 2008 presents a

perfect platform to validate this

hypothesis my co-authors and I have done

extensive research on this subject

in a project that was sponsored by New

York University stone school a National

Stock Exchange of India we found that as

early as 2010 algorithms accounted for

15% age of trading in big stocks

subsequent research shows that the share

had increased to 70 percentage by 2013

within five years this new breed of

traders had captured 70 percentage of

the market right the message is loud and

clear machines dominate trading in

markets this is the new normal

whether it is India or us machines

dominate trading in US markets let’s

next look at a dramatic illustration of

how this race for higher and higher

speeds has played out in the markets in

his bestseller flash boys the author

Michael Lewis introduces us to Dan

Spivey a trader based out of Chicago

like other traders he was very

frustrated with the poor transmission

speeds provided by the traditional

carriers how bad was it you may wonder

in 2007 it took 16 milliseconds for a

signal to do a two-way trip between

Chicago and New Jersey let’s put that

number in perspective right a blink of

an human eye takes 300 to 400

milliseconds thousand milliseconds is

one second right so by the time we blink

our eye a signal would have made twenty

round trips between Chicago and New

Jersey we might find this positively

baffling but the traders founded

woefully inadequate right so smiley

sensed a business opportunity if he

could find a faster way of communicating

data between these locations the speed

bandits would pay him a handsome reward

so he started a telecommunication firm

the name of the firm was spread networks

and his objective was to build a

straight a line as possible between

these two locations why because when spy

we started examining the cable roots of

the carriers we found that there are

lord of places where the roots were not

straight that makes sense right if you

have mountains or rivers the tables have

to go around them and not through them

however these twists and turns greatly

resolve in drop of transmission speeds

so spy we decided to build a straight a

line as possible

it meant literally blasting holes to the

mountains and digging tunnels under the

riverbed which he did finally Spivey had

a line through which he could transmit a

two-way signal within 13 milliseconds

right so if you are anchoring yourself

in the eye blink world we went from one

by twentieth of an eye blink to one by

twenty-fifth

of an eye blink mind boggling right so

how much did it cost by B to build this

build in life 300 million dollars just

so that hft traders could shave off

three milliseconds or one by hundreds of

an eye blink the arms race was truly on

despite this high stake race the beauty

about hatchapee was that they managed to

stay away from the public spotlight for

a very long time that is until the day

of the flash crash suddenly the acronym

hft started popping up everywhere and

the Google search for the keyword

hatchapee went through the roof that’s

what we do then you don’t know something

right we just go ahead and good so

everybody started looking what hey chip

D was but what actually did happen on

that day at 2:32 p.m. a mutual fund

group not a chip t remember send a huge

cell order to the market due to the

intense selling pressure the prices

started falling initially hfts viewed

this as the temporary aberration and

started buying but when the prices

continued to fall they sold whatever

they had bought earlier some of them

continue to aggressively south and some

decided to stop trading as a result

there is hardly any buyer in the market

and the market tanked so here is a

remarkable statistic between 245 13p

to 4527 p.m. a total of 14 seconds hft

is traded about 27,000 contracts or

roughly 2000 contracts per second or

thousand contracts per eye blink right

what was the role of the hfts in this

crash this is where a lot of ambiguity

is and that’s why we need proper

research to educate us a recent paper by

researchers from MIT at University of

Maryland

among other schools summarizes it nicely

they say while ketchup teas did not

cause the flash crash they contributed

to it due to their excessive training

this is not semantics right this is not

a trivial case of potatoes potatoes

tomatoes tomatoes it’s a sharp

difference between what they did and

what they were believed to have done now

so what is the learning what have you

learned in the past six years here is

what we have learned algorithms

specifically Hatcher T’s dominate

trading in most markets that’s the new

normal as soon as a flash crash

demonstrated this new normal

unfortunately is inherently unstable the

billion dollar dollar question or should

we say the trillion dollar question is

how do we improve the stability of these

markets researchers regulators

policymakers exchanges have thrown their

hats in the ring unfortunately we still

do not have a definite answer until we

find an answer we can only hope that

where every time HF please go on a

rampage like this we somehow managed to

doze off

this was 23rd April 2013 and around 1 7

at 107 on that day the markets witnessed

a micro crash losing about 200 billion

dollars in investors but what happened

on that day on that day The Associated

Press Twitter account was hacked so the

trading algorithms read the fake tweet

then realized that the tweet was fake

started selling and the market crashed

all of this happened within one minute

all of this happened before

Associated Press realized that his

account was hacked right

so in summary right in the olden days

what would that trade are done the

trader would have just picked up the

telephone and asked hey did they really

bomb the white house but now by the time

the trader picks up the phone unlocks

the screen dials the number and says hey

a gazillion orders would have gone to

the exchange The Shard is a crazy a fast

word out there thank you [Applause]

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