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by mrchicity 2905 days ago
Interesting idea, but how would you deal with these issues:

1.) Randomizing who receives contentious trades will just encourage order splitting and gaming. Sure some of that can be banned, but nothing stops big firms from putting each trading group into different legal entities or other tricks.

This also discourages traders from bidding their true most aggressive price. In time priority, you must, or someone else will snatch your trade. If you remove the reward, why take the risk?

2.) Being fast would still matter. Reality isn't quantized, so having access to relevant real world information or a proxy for such (trading activity in other markets or products) would still be an edge. Existing quantized trading points such as exchange auctions are still latency sensitive.

3.) The modern marketplace is interconnected. No ETF market maker will quote a tight spread if he can't confidently hedge his risk in the individual stocks. Going into a one second auction with random allocation is a lot riskier than just hitting the bid on Nasdaq, maybe paying an extra penny in the rare case when you're slow. A lot of liquidity comes from people running these arb/stat arb trades. It tightens spreads and helps keep prices in line. Why harm it?

4.) There is more to HFT success than speed and I don't think this would hurt them too much or take us back to 1997 with day traders sitting at home making big money. Virtu or some other HFT shop was the biggest trader on IEX, and they have a speed bump similar to this, just less extreme.

1 comments

For 1), I'd randomize with proportional unit (share) representation, and I'd certainly be open to rule-prioritized execution (e.g. most-favorable taker first) if it didn't lead to degenerate incetives. Smart market design can incentivize people to play at their best price. For example: locational marginal pricing in wholesale energy markets...

2) I agree that the real world is quantized, but I think that a settlement tock to the bidding tick could be used to reduce the value of proximity. IEX actually implemented general latency with long runs of fiber, which is a really elegant fix. They couldn't make the rest of the world latent, so it's something like 700 microseconds, enough to remove colocation advantages, but only enough to solve for New York.

3) As far as I know, HFT's like to play in limit order and derivative books. It's where practices like flashing and spoofing have come from. Market orders are fraught with peril, especially if you don't know the matching rules for the exchange. As far as tightening the spread and aiding price discovery, I don't think that those two things are the same. If a security has naturally low volume, responsive high frequency trading can effectively be predatory.

4) I agree that there is more to HFT than just speed, but I view high frequency temporal arbitrage as an unnecessary market feature that provides the illusion of liquidity right up until that liquidity would truly be useful (since robots get benched when things go strange).

Granted, the temporal steps that I'm advocating here are a little provocative. The US could be solved in something like 200ms, and larger global markets, like currency exchange, are already fairly decentralized (though not as much as they used to be, as far as I know).

Either way, I don't think that NASDAQ can assure global temporal coherence, especially without controlling the entire network. Given that, it makes sense to design robust systems that don't pivot into rare modalities in exceptional cases. Just pull clock slew off the board.

1.) If you do it proportional to shares, then it introduces bad incentives to oversize orders. There's a reason why almost every market in the world uses price time priority in a realtime two sided auction.

2.) What problem does this solve? Proximity is freely available and relatively inexpensive. Barriers to entry for professional traders are much lower than the days of buying exchange seats. 10s of thousands a month sounds like a lot, but it's nothing compared to the costs of running a trading operation.

You could give every man, woman and child a rack at Nasdaq with a nanosecond trading system, and they wouldn't make any money. Proximity only matters to traders running latency sensitive strategies. These strategies have low margins per trade and can only profit through scale. Running them requires robust systems that take years to develop, capital, smart researchers, and data.

3.) Spoofing is illegal and people go to prison for it. HFT is just a catch all term for executing short term trading strategies with a computer. Most HFTs make their money through market making, arbitrage, stat arb, or some blend of those. All profitable trading can be cast as predatory, but that doesn't make it bad. Having accurate prices and more quotes in the market is a public good.

4.) So you believe it's good if S&P 500 futures go up 2%, nobody arbitrages the S&P 500 ETF, and John Smith comes to the exchange and sells his ETF shares 2% below their value? I'm guessing not.

Odds are you believe arbitrage and efficient pricing are important. If you believe that, then someone should do those trades, and they'll earn profit as a reward for correcting the price. Why shouldn't it be the person or machine who does it first and for the lowest possible margins?