lzhou

Joined 17 years ago

Karma
113
Submissions
20
Member since
Feb 14
Co-founder of www.renthop.com

Personal Website: www.lrzhou.com

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Recent submissions

Comment · 9 months ago
it's actually pretty funny since opus will suggest both of these with enough prying (though with a single-prompt it might not try it).
Comment · 9 years ago
Assuming your result set isn’t massive, it’s not very hard to have a 30-40 line array function (that takes a query) and returns a sql resultset.
Comment · 10 years ago
John Henry dies at the end of the story.
Comment · 11 years ago
I find it amusing that there seems to be a cargo cult going on with respect to Steve Job's fashion.
Comment · 11 years ago
A technology-enabled brokerage is very different from a technology company with brokers. First, there is a cultural difference in who the heroes of the company are. Also, the latter is much more capital intensive.

I suspect they probably would have needed another 20-30MM to really get moving on the latter. A lot of that money going to consolidation of existing brokerages and monopolizing listing content.

Being a neutral aggregator is mutually exclusive from being a dominant brokerage.

Comment · 12 years ago
I think 4) holds.

We have 2 spectrums for all known strategies (the amount of gold in the veins is another question):

* Strats that are automatable vs non-automatable.

* Strats that are unique (known to a few) vs well-known strats

Automatable:

Well-Known - This is where HFT becomes an engineering problem. It's also the easiest business decision to make. I hire some engineers + buy some computers and I can mint some money for a time. This is also a race to the bottom -- where there will be some easy money to be made at equilibrium, but it'll be unsustainable for HFT firms at the margin. I would say manual trading has 0 impact here -- and they'll likely get crushed.

Unique - These are strategies that only a small set of firms know. Eventually these strategies become well-known as people move around companies. There must be some secret strategies, though. Otherwise, why would Rentech & Citadel sue their own employees (unless we are to believe Simons & Griffin are simply vindictive). I think manual trading could work here if there is a strategy that simply haven't been discovered by the HFT & quant. It's might be hard, but not impossible. These secrets aren't anything you'll find online or in some trading forum, though. Or perhaps they are, but no self-respecting quant would go there (lest they become laughing stocks in their fund).

Non-Automatable:

Well-Known - PE is an example of one. In terms of liquid assets, maybe penny stocks are another area. If a group of "manual" traders couldn't get permission to delve there... it's probably even harder for a quant fund. It's also the territory of insider info and rumors.

Unique - Maybe being there for the liquidity crashes I stated earlier is a good example. But there are certainly non-automatable unique strats around.

Depending on how much gold you believe is in the veins, all strategies are heading towards automatable & well-known. However, in the interim, I can see manual traders still making money (even with a sharpe > 1). In fact, I would say there are well-known strats you can execute manually (in say, your PA, that return sharpe ~0.8ish).

Comment · 12 years ago
I'm not sure that's completely true.

1) Are there places / markets that ST Arb and HFT won't go because it's too illiquid or too idiosyncratically volatile?

2) Are there edges so small that you won't chase?

3) Are there one-off opportunities (2010 flash crash, UST flash crash recently, etc.)?

4) Is there a set of strategies that manual traders know (which they should probably transfer to HFT strategies) that the HFT/ST arb shops don't know?

I think the answer to all of those questions is "yes". They probably take on a lot more risk per trade. They would also be better served by automating their strategies. But I think it's not as cut and dry as you state.

Each individual trader might be "amateur" -- but the firm as a whole might end up with a decent return / risk.

Comment · 12 years ago
Another huge thing -- Data quality. Bloomberg gets free crowd-sourced feedback on their data. Apparently, there are hedge-funds (especially for less liquid assets) that make money by finding broken data, buying something cheap (or shorting) and then calling BBG to fix their info.
Comment · 12 years ago
That's when the flustered interviewee can either fight (patch his solution) or flight (start all over using a class with refs). The most obvious patch is to use a large hashmap instead of a massive array. Still inefficient, but no longer that desperate (and actually has some added benefits).
Comment · 12 years ago
So the old - allocate a massive array, then use 2n+1, 2n+2 for the left/right children wouldn't have flown with you huh?
Comment · 12 years ago
For an API, you can also try http://open.mapquestapi.com/nominatim/ (which is kinda free -- and uses OpenStreetMap data).

The biggest problem we've had is changing non well-formed addresses / ambiguous addresses into canonical addresses with lat/lng. Google Maps wins on that front.

Comment · 13 years ago
Aside from the total debt vs median wage issue - the chart also doesn't mention that THE recession that happened. What happens in a recession? 1) parental wages and/or job security are lower [ie, more debt needs to be taken on] 2)median wages coming out are lower. That may be partly the cause of the relationship.

Median wages dropped (starting in 2007) because of a recession, and we are still in the adjustment process of that (ex. on the wage side). We notice that post popping of the 2001-2002 bubble, the median wages actually increased into 2007.

I don't have all the facts, but the chart is misleading.

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