[oangemangut]

If you look up RegNMS the goal is to make public markets fair by having rules that have to be met in order to trade. Dark pools allow participants to 'hide' information that's not public. It is mostly about the order books. If dark pool sell order for 1B of TSLA stock goes on the order book, only other members of the pool get that information. The dark pools are required to still follow RegNMS rules for trade prices, but there is an inherent asymmetry in the market information in this case as the dark pool participants can see the public markets and their dark pool in order to make trading decisions.

In your neighbor's house example, it would be like if there was a street market auction for trading cards happening in your neighbor's front yard, but in the house your neighbor and another neighbor had gotten together to trade 100x the average #of cards using the prices they hear from outside, and the people outside only see the deal they made after it's done.

[roenxi]

And what would the problem be with that example? It seems everyone has agreed on a fair price and is trading on it. There isn't any incentive for the private traders to trade at a different price or one of them is getting ripped off due to the arbitrage potential. And they don't believe that publicising the trade would move the price or - again - one of them would have an incentive to do so because it'd move in their favour.

I don't see how I'd be disadvantaged as any actor in that scene.

[hattmall]

You are disadvantaged as an outsider because you don't know who is buying or selling and how much they are trading. You don't know the demand levels at various price points. If, for example, you want to buy Stock A which is currently trading for $5 and sell it for $6, but there is someone trying to sell 5 million shares for $5.05 but you can't see that you can't make an informed decision on ideal price points for your trade.

[Dylan16807]

> you want to buy Stock A which is currently trading for $5 and sell it for $6

It sounds like I'm asking for a pony in this scenario. I shouldn't expect to get that.

If I want to buy at $5 and hold it for more than a day, I don't think the secrecy of that big sale really affects me. It'll be over soon enough.

[nairboon]

> If I want to buy at $5 and hold it for more than a day, I don't think the secrecy of that big sale really affects me. It'll be over soon enough.

It does, it means that you could've gotten the stock for maybe $4.9 instead of $5.

[roenxi]

^_~ How? Nobody was selling it for $4.90 in that example.

[nairboon]

Although the above example was missing some details, I suspected it was meant to illustrate the following effect: The public last price was $5, so bid/ask will be around that price let's say 4.99/5.01, if you buy with a market order you'd pay approximately $5 ($5.01). But if there is a new large sell order for 5 million shares at 5.05, then the market would react to this information and adjust bids & asks. For illustrative purposes it could be possible (if the 5 million order is rather large in comparison), that the new bid/ask would be 4.89/4.91 and you'd get your shares for around $4.9.

[infecto]

You are not disadvantaged because you are not buying 5mm shares. I like to think of it closer to volume pricing rather secret pricing. You could definitely do retail level volume on a pool but you will be paying for it and that cost will generally be higher than any "savings" you may get in price.

Its similar to complaining that someone is buying eggs at wholesales prices while you are paying retail.

[derf_]

Ask yourself: if 99% of the volume is being traded inside the house, how much easier is it to move the "fair" price in that street auction?

[infecto]

Its more like 50% of total volume being traded in dark pools. Your price argument does not make much sense though, the beauty of western markets is that folks are so opportunistic that someone will exploit any information asymmetry so your argument would not hold up. Also at the end of the day its not like buyers and sellers in a dark pool know "the price" of what they are trading, sure they have ideas of where they might be buyers and sellers but they are still using the lit market data to inform their decision.

[chii]

but people trading inside the house would know this already. If they suspect that the fair price is being manipulated, why would they continue to buy inside the house?

[JumpCrisscross]

> If you look up RegNMS the goal is to make public markets fair by having rules that have to be met in order to trade

That was the goal and it failed at it in everything but the most technical sense. Why two people coming to a handshake deal about the price of their property is illegal is insane. I previously bought the argument about propensity for fraud. But if we’re normalising crypto, there is zero need to continue treating stock like it’s radioactive.

[thaumasiotes]

> In your neighbor's house example, it would be like if there was a street market auction for trading cards happening in your neighbor's front yard, but in the house your neighbor and another neighbor had gotten together to trade 100x the average #of cards using the prices they hear from outside, and the people outside only see the deal they made after it's done.

Isn't that how everything is traded? Am I supposed to be outraged that everything I buy retail also exists in a wholesale market?

[oangemangut]

For these institutional traders, the pools offer them opportunities to trade with a small set of counter parties that also have deep deep liquidity, so in a sense it is kind of like the wholesale markets for retail. Orders hit the book in the pool and they don't have to worry about 'current retail' stock and can trade massive blocks with trade certainty.

[gruez]

>Dark pools allow participants to 'hide' information that's not public. It is mostly about the order books. If dark pool sell order for 1B of TSLA stock goes on the order book, only other members of the pool get that information. The dark pools are required to still follow RegNMS rules for trade prices, but there is an inherent asymmetry in the market information in this case as the dark pool participants can see the public markets and their dark pool in order to make trading decisions.

But traders can easily hide the size of their "true" order by breaking it up into chunks and constantly refilling the order if it's taken? This is basically trading 101. If you want to do a big selloff, you're not going to dump all of that in one order.

[rtkwe]

But by breaking up the order they have to wait and the market can move in reaction to their sell off unless they do it very slowly. Dark pools can completely hide a large sell or buy order from the market long enough to execute at the current strike if there's another member in the pool buying. They wouldn't use it if it didn't give them an advantage because it costs more than regular trades.

[gruez]

>But by breaking up the order they have to wait and the market can move in reaction to their sell off unless they do it very slowly

it kinda works out because the other side is also smart and will also break up their orders. Putting in a massive buy order is a good way to pay through the nose.

[rcxdude]

>In your neighbor's house example, it would be like if there was a street market auction for trading cards happening in your neighbor's front yard, but in the house your neighbor and another neighbor had gotten together to trade 100x the average #of cards using the prices they hear from outside, and the people outside only see the deal they made after it's done.

I mean, that's literally what happens with trading cards. It's super common to base face-to-face deals (whether for cash or trades) on internet pricing, including very big ones. (the trading card market is a lot less liquid, though, so it's also common for there to be a fairly big discount or premium on those prices in the deal for various reasons)