Understanding Stock Market Returns

Earlier today I had a short conversation on Twitter with financial markets guru Deepak Mohoni, one of whose claims to fame is that he coined the word “Sensex”. I was asking him of the rationale behind the markets going up 2% today and he said there was none.

While I’ve always “got it” that small movements in the stock market are basically noise, and even included in my lectures that it is futile to fine a “reason” behind every market behaviour (the worst being of the sort of “markets up 0.1% on global cues”), I had always considered a 2% intra-day move as a fairly significant move, and one that was unlikely to be “noise”.

In this context, Mohoni’s comment was fairly interesting. And then I realised that maybe I shouldn’t be looking at it as a 2% move (which is already one level superior to “Nifty up 162 points”), but put it in context of historical market returns. In other words, to understand whether this is indeed a spectacular move in the market, I should set it against earlier market moves of the same order of magnitude.

This is where it stops being a science and starts becoming an art. The first thing I did was to check the likelihood of a 2% upward move in the market this calendar year (a convenient look-back period). There has only been one such move this year – when the markets went up 2.6% on the 15th of January.

Then I looked back a longer period, all the way back to 2007. Suddenly, it seems like the likelihood of a 2% upward move in this time period is almost 8%! And from that perspective this move is no longer spectacular.

So maybe we should describe stock market moves as some kind of a probability, using a percentile? Something like “today’s stock market move was a top 1%ile  event” or “today’s market move was between 55th and 60th percentile, going by this year’s data”?

The problem there, however, is that market behaviour is different at different points in time. For example, check out how the volatility of the Nifty (as defined by a 100-day trailing standard deviation) has varied in the last few years:


As you can see, markets nowadays are very different from markets in 2009, or even in 2013-14. A 2% move today might be spectacular, but the same move in 2013-14 may not have been! So comparing absolute returns is also not a right metric – it needs to be set in context of how markets are behaving. A good way to do that is to normalise returns by 100-day trailing volatility (defined by standard deviation) (I know we are assuming normality here).

The 100-day trailing SD as of today is 0.96%, so today’s 2% move, which initially appears spectacular is actually a “2 sigma event”. In January 2009, on the other hand, where volatility was about 3.3% , today’s move would have been a 0.6 sigma event!

Based on this, I’m coming up with a hierarchy for sophistication in dealing with market movements.

  1. Absolute movement : “Sensex up 300 points today”.
  2. Returns: “Sensex up 2% today”
  3. Percentile score of absolute return: “Sensex up 3%. It’s a 99 %ile movement”
  4. Percentile score of relative return: “Sensex up 2-sigma. Never moved 2-sigma in last 100 days”

What do you think?

How do i describe my job?

One of the “problems” with my job, if I can describe this as one, is that it’s tough to explain my job to a layman. There are multiple levels of disconnects here, and multiple “pitfalls”, if I can call them that. So when someone asks me about my work, it gets tough indeed to describe to any degree of accuracy while at the same time being concise, and at the same time talking in Kannada.

I am a quant at a hedge fund.

My work involves coming up with trading strategies, and then developing them to a level where I can have the ultimate fighter – a computer – to trade using these strategies. Then, I will need to figure out how the computer is going to implement these strategies and this part involves some heavy engineering work. And finally I code. Ok now I haven’t been accurately able to describe in one paragraph, writing in English, about my job. How do you expect me to describe it to the layman speaking in Kannada?

Coding is a part of my job, but I’m not a coder.

I deal with financial products – equities and equity derivatives. But I’m strictly not a finance guy – as far as I’m concerned, each security is just a time series. A time series on which I can trade and make money. In fact, apart from my short stint selling interest rates swaps in London, I haven’t really done any finance. My entire view of the markets is based on my idea that a security is just a tradeable time series. I think I should do a separate post on that. Anyways, I’m not strictly a finance guy also.

One of my degrees is an MBA. A PGDM to be precise, from IIMB. But I’m not a manager also. I don’t manage people apart from myself.  I’m not sure I’ll find that interesting either – I sometimes think managing is too fighter a job for me.

And so on.

And then, I work for a hedge fund. Most people don’e have a clue what a hedge fund is. I sometimes make an approximation and tell them I work for a mutual fund. And immediately I get bombarded with questions like my opinion on whether the markets will go up or down, and about how long the recession is going to last. And then there are those who start telling their sob stories about their investments in the markets when the Sensex was at 20,000 and about how markets can’t be trusted any more.

Another level of contradiction is that I’m based in Gurgaon. All finance companies are supposed to be in Bombay, right? Surely, given that I’m in Gurgaon, I must be doing some back office kind of work?

Last night my uncle was filling up some arranged marriage exchange registration form for me. And he asked me to describe my job in a short phrase. I immediately came up with “trader” and that got quickly shot down since that would give the image of a lala sitting behind huge weighing scales. Next I tried “financial trader” and “quantitative trader”. No go.

Then I wanted the simple “quant”. My highly stud uncle himself had trouble exactly figuring that out, so fat chance anyone would appreciate that. So out again. I relaxed constraints a bit and said “hedge fund professional”. But most people wouldn’t understand “hedge fund”. “mutual fund” was no go for a written form. “quantitative analyst” was considered too country by my uncle. He then asked me my designation. “Associate” doesn’t mean anything, he said and shot that down too.

Sometimes I wonder if I’ve unnecessarily complicated life for myself by choosing the path that I’ve chosen. If I were working for some software company I could’ve just written “software” over there and all would’ve been fine. The whole world would’ve understood, or at least claimed to have understood. Or even better, if I were living abroad, I wouldn’t have even been required to say that much. I’d’ve been just qualified as a “foreign huduga”, with most people not even caring for which city I was in.

For the record, my listing application records my profession as “financial services professional”, as country as it sounds. This was the only middle ground where my uncle and I didn’t disagree. And in it went. It increasingly looks like I’ll have to put fundaes to Cesares about why the stock markets have gone down in the last one year in order for them to allow their daughters to marry me. I have half a mind to start describing Ito’s lemma the next time someone asks me where the markets are headed. I’ll probably start off describing to them a random walk. And say that it’s a drunkard’s walk. And perhaps use that to change the topic. I think I might need to start practicing this. In Kannada.

I’m a quant at a hedge fund.

Bloomberg Watching

Two weeks back we were all given dual screens at office. A couple of days after that, those of us that had joined recently got Bloomberg logins. It’s a very restricted version of Bloomberg, with most of the strong features having been disabled. One feature that is enabled, though, is to get the graph of the daily price movement of a security, or an index.

It is necessary to have hobbies at work. It is humanly impossible to concentrate solely on the work for all the eight or ten hours that you spend at office. You need distractions. However, in order to prevent yourself from being too distracted, it helps having one or two very strong distractions. Distractions which can crowd out all other distractions. They can be called “office hobbies”.

In the past, my office hobbies haven’t really been constructive. In my first job, I was part of a PJ Club, and we would exchange horrible jokes. By the time I got to my next job, I had been addicted to Orkut, and kept refreshing it to check if I’d gotten any new scraps. Of course, when there is a cricket match on, the Cricinfo screen makes for a good office hobby. In the last ten days, the World Chess Championship has served my evenings well. However, it is important to have a sustainable hobby which could also be constructive. One which might have a small chance of making impact on your work. And most importantly, it would be ideal if the boss doesn’t really disapprove of your office hobby.

For the last week and half at work, my right screen (remember that I have two screens) has been reserved for Bloomberg Watching. A Bloomberg window is open there in full size, and I would’ve usually put the daily movement graph of the Nifty there. And it updates real-time. It’s like a video game. I just sit and watch. And get fascinated by the kind of twists and turns that the markets take.

Twenty years back, I would spend my evenings in the courtyard of my grandfather’s house in Jayanagar watching ants move about. I would be fascinated by their random, yet orderly movements. I would spend hours together watching them.

Around the same time, I used to play another game. I used to splash water on the (red-oxide coated) walls of my loo, and watch the different streams of water flow down as i crapped. I would get fascinated by the patterns that the water droplets would form, the paths that they would take, the way they would suddenly change speed when they intersected, and so forth. I would end up squatting there long after I’d been done with my crap.

So what I’m doing now is not exactly new. I just watch a point move. Orderly from left to right. Wildly fluctuating in the up-down direction. I look at the patterns and try to guess which animal they look like, or which country they look like. I get fascinated by the sudden twists and turns that the curve takes, and wonder about the collective wisdom of all market participants who are faciliating such movement. I occasionally scream out to my colleagues saying stuff like “nifty below 2600!” and they respond with a “behenchod…” or some equivalent of it.

As the day wears on, I realized that some animals I had recognized earlier in the day are hardly visible now. They are but specks in the larger graph that is the day. And then I realize that unless there was something truly special, the movement of the day will also soon be lost. It will be available for download from the same Bloomberg terminal but that will be about it. And so forth.

Occasionally I catch some unsuspecting soul on my GTalk list and spout such philosophy. I tell them about how after a while everything becomes insignificant. About how we will always be just small players in the larger system. The smarter among them will add their own philosophy to mine, and sometimes we come up with a new theory. The not so smart among them – they will ask me about my views on the market. And what would be good picks (this has been a regular question I’ve been asked ever since I got back into the finance industry but more about that later). And then they say something like how terrorists are the reason the stock markets are plunging, and how the government should protect investors’ money and stuff.

Some day I hope all of this will be useful. Some day I hope my eye for recognizing animals and countries where none exist will enable me to come up with some earthshaking strategy, which can make millions for my fund. However, now that doesn’t matter. All that matters is the unbridled joy of watching the ticker move up and down. Rise and fall. Take baby steps, and the occasional giant leap. It’s surreal.