Any portfolio math geniuses have a sec?

Hi all,
Hoping someone can help me out with something that’s been vexing me for some time. Basically, I’m wondering how to figure out how much portfolio exposure one would generally need to generate a certain yearly return. I know there are tons of caveats here, but it’s pretty obvious that the odds of generating a 10% yearly return on $100mm dollars with a one lot of e-mini’s are pretty slim.

I size positions using the “Percent Volatility” method.

X% Vol Postion = (X%*Trading Capital)/($Value of an average day’s range)

$ Value of a Day’s Range = 21-day Average True Range x $Value per point

So, for example, if the average range in ten year note futures was 1 point, I was trading $100mm, and I wanted a 2% vol position, I would need to buy (.02*100mm)/$1000 = 2000 lots.

To keep it simple let’s just pretend for now I’m only running one position. So if I’m tasked with making saying 12% a year, while maintaining a Sharpe ratio of 1.5, and Bond’s have a historical volatility of X, what formula would I use to determine what %Vol position I would need, on average, to make these numbers?
Thanks so much! - MD

5 Comments
 
Best Response
Aggmonkey

Maybe i'm missing something, but why don't you just use historical return percentages for different asset classes/styles and back into your asset allocation that way.

Are you trying to generate x% return only with futures on the 10y?

this.

I personally don't use futures so I don't know the math for target return there but basically you can get any target return in theory from the right asset allocation. here's how you should structure your model:

  1. determine what time frame you're looking at for returns, sharpe ratio, etc (1y,3y,5y, etc the numbers will be very different). I'd recommend 10y so you capture the latest recession
  2. determine which asset classes you want to include/exclude, and get as granular as you'd like, but ensure that the data are there (for example, hedge fund indices are unreliable, as are certain EM indices because they're cap weighted)
  3. determine your targets (return, sharpe, etc)
  4. use whatever method you want (software, morningstar hypo, trial & error) to determine the right mix of investments to get you to your target return and sharpe
 

Thanks for your answers thus far. I'm really an outright speculator so historical returns doesn't quite fit for me. It's going to have to be something based on historical volatility. For instance, if I'm trading gold, historical returns doesn't make much sense, but if I know what my typical sharpe ratio is, and know the current historical volatility (say for the last 250 days) then I should be able to come up with some position size that "makes sense."

Maybe it will help if I ask like this:

If historical volatility on the stock market is 10%, I have a sharpe ratio of 1.5, then what kind of average daily percentage swings should i expect to be able to make 15%?

 

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