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Comment by dguaraglia | Hacker News Reader

Right, so the reason all these banks run extremely expensive HFT divisions is to guarantee the best possible price to their customers. Got it. I'm glad they have our back! /s

As someone who has actually seen the scenario described above play out, I'm not so sure: stock doesn't move for minutes at a low volume time of day, the moment I place my limit order the price is suddenly higher than my limit; rinse and repeat. I've seen this happen enough times to make me believe Reg NMS is just another regulation they've found a plausible deniability around (BTW, before you tell me "prices going up when you place a big order is how the market works", I've tested this with 100 share orders, so there was no order split going on. I still got priced out.)

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I think everyone is right to be suspicious of payment for order flow, on the surface it does seem hard to get the incentives right.

That said, in your scenario (you were prevented from trading) how does anyone make money? You were (probably) paying for a trade (which did not happen) and you were using infrastructure that costs money (placing orders), and no one was able to trade against you. That is not a great business model...

Also, none of the groups we are talking about are banks.

My guess is that the algorithm doesn't expect to make money out of that particular order, but rather guesses this is a bigger order that is being split (laddered if you will) into multiple small orders at different acceptable limits. The product I used (Interactive Brokers interface) offers that laddering strategy as an option when trying to make big purchases.

Oh, and BTW, order cancellations cost money. Cents, sure, but when you are making money on a 1c spread, you would also benefit from a 1c cancellation.

Other than that, I've been tempted (and many times succumbed) to raise the limit just to get that trade. And then you see the price go up again before your order goes through. It'd be hilarious if it wasn't infuriating.

If the order is coming from a retail brokerage that's a terrible guess - how often do you think someone goes into ETrade and tries to move $20M of GOOG?

Big orders come from institutional investors. Those are explicitly the orders that market makers are trying NOT to trade against, and that's why they try to buy order flow. Order flow is known to come from players who aren't making big orders.

As I clarified on the other comment, I meant "big" as in "retail big" (i.e. a couple thousand shares of TSLA, or any order big enough to be fulfilled by matching several sell orders.) I can't really recall that many of my orders being filled below my limit price, unless I was willing to increase the limit by a few cents over the NBBO.

If the ask price for a security is, say, 5.51 and I put my limit at 5.51 the chances of getting the order filled were pretty low. If I was willing to go to 5.53 the chances would increase, if the order was 5.55, I'd probably get a fulfilled order at an average price of 5.53 or so. Not a huge difference on small orders (say 1000x2c = $20) but enough to make a "big" volume, small spread strategy pretty much useless.

The price can change from the time you place your order to when it arrives at the broker. This is especially likely if you are an active trader chasing news or momentum where others are likely trying to buy at the same time. It's like aiming a rocket, or in your case, an old Honda Civic, at a fading star. Have you looked at what the book state was after you placed your order in the cases where you don't fill? If you have a working order priced through the market that's unfilled, take a screenshot and name & shame your broker here.

Just chiming in to point out that 'yummyfajitas, 'chollida1, and 'kasey_junk are all current or former trading engineers.

I imagined as much. That's what I love about HN, you do get some details on how the sausage is made from the sausage-makers themselves.

Suppose you place a limit order to sell STCK for $x and I only execute it (giving you $x) if the price goes above $x+1. Someone's making $1 on that spread and it definitely isn't you.

If I accept a limit order from you to sell for $x and the price goes down to $x-1, someone lost $1 and it sure wasn't you.

All you've discovered is that when you sell a stock, you lose both the upside and the downside.

No, the broker can just not execute the limit order. There's never downside for the market makers.

You are confusing "accept a limit order" with "purchasing a call option".

Once you've accepted the order you are legally obligated to deliver in T+3 days. If you fail to deliver you pay big penalties, your broker shuts you down, all sorts of bad things.

In my experience with brokers like Schwab, placing a limit order is no guarantee of execution, even if the market price reaches the price specified in the limit order.

I think you're again confusing terminology; you're referring to placing an order, which is obviously no guarantee of execution, and Chris is referring to what happens after your order is executed.

They don't. They run them to make a profit off the spread.

The purpose of order internalization is to trade against uninformed participants (Joe 401k), without risk of accidentally trading against bigger informed players (Bill Ackman). If you are trading against uninformed players, your risk is lower and you need to offer a better price to get order flow.

Read these two blog posts for a bit more detail on price discrimination on the basis of delta toxicity (albeit not in the order internalization context).

https://www.chrisstucchio.com/blog/2014/fervent_defense_of_f...

https://www.chrisstucchio.com/blog/2014/mark_cubans_hft_idio...

If you want to argue that something nefarious is going on, go ahead and describe the mechanism. But whatever it is, it's almost certainly not the mechanism chollida described.

I have no idea what the mechanism is, but there's definitely something extremely fishy when you don't see the NBBO move at all for an hour and it magically moves the moment you place an order. I wouldn't even know who is to blame: Interactive Brokers? Other HFT players? My incredibly consistent bad luck at placing an order at the exact same moment the price goes up, even after observing the price being stable for an hour (again, at a very low volume time of day, like 3pm PST)?

I clearly don't understand what's going on under the table as well as you would, and because the strategy I was toying around with at the time was basically big volume on small spreads ("big" for a retail guy, obviously, I don't have millions at my disposal) it was shot to crap by these magic changes.

So I did the sensible thing and closed my account. Off to invest in less volatile assets, if I can find any, heh.

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