Hacker News Reader

minimaxon Parker Conrad Steps Down as Zenefits CEO

It kind of sounds like Zenefits is looking at some heavy (multi million dollar) fines, and they're trying to drive the narrative before fines and regulatory actions are announced.

minimaxon Alphabet Becomes the Most Valuable Public Company in the World

Yes. It's because of the idiotic way the Dow formula works. The Dow is a price weighted index. To compute the value of the Dow, you sum the per-share prices of the constituents and divide by a magic divisor. So a $50 move in GOOG (~6.6% change) and a $50 move in AAPL (50% change) would have the exact same impact on the value of the index. The kludgey solution to this problem is just to not incorporate high priced stocks into the index.

Incidentally this is why when you hear anyone quoting the Dow you can tell immediately that they are either clueless or an innumerate moron.

minimaxon San Francisco Bubble

local IPAs are $15

Is that actually true?

minimaxon High-Speed Firms Now Oversee Almost All Stocks at NYSE Floor

Do you think there are monopolies in electronic market making? I think there are tons of firms out there trying to be good at it in different asset classes, and a few that are really good at it in lots of asset classes. I'm not sure it looks like "a few natural monopolies."

minimaxon High-Speed Firms Now Oversee Almost All Stocks at NYSE Floor

I thought you were making the argument that reducing tick sizes would reduce the amount of effort put into reducing latency (or reducing the overall amount of prop HFT volume), but I guess I was wrong about that. The idea that reducing tick sizes would ultimately reduce market maker risk by making certain quoting strategies less viable is interesting.

minimaxon High-Speed Firms Now Oversee Almost All Stocks at NYSE Floor

I think a better way to change exchanges is to dramatically decimalize the price levels.

The idea that reduced tick sizes would force traders to compete on price rather than time is a popular HN market microstructure solution, but it's wrong or at least partly wrong.

1) Liquidity taking strategies will still "compete on time" in order to trade at the most favorable prices. Market making strategies will still "compete on time" in order to avoid getting picked off.

2) Inverted fee venues and midpoint order types offer sophisticated traders the opportunity to trade at prices within a 1 penny spread. If you watch the tape for a stock like ZNGA you will see this type of trading.

3) There are a number of high priced / high volume stocks that don't trade at a penny spread. GOOG is a good example. Do you find GOOG trading to be somehow cheaper, more orderly or efficient than e.g. MSFT? The GOOG spread is almost never a penny and is regularly over 20 cents. If the benefits are there, they ought to be obvious.

minimaxon High-Speed Firms Now Oversee Almost All Stocks at NYSE Floor

... they never seem to answer the question of why someone who is not an HFT firm would want to trade on an exchange that caters to high frequency traders (as basically every exchange does).

There are a number of incorrect assumptions built into your comment (most notably that prop HFT are the only ones using algos to trade), but the simple answer to this question is that those exchanges have larger displayed size at better prices.

minimaxon Sort Faster with FPGAs

I wouldn't say it was a complaint but the k is definitely what caught my attention.

https://en.wikipedia.org/wiki/Big_O_notation#Multiplication_...

minimaxon Sort Faster with FPGAs

I agree with you and I meant it as a genuine complement.

minimaxon Sort Faster with FPGAs

O(kN)

If this is trolling you're doing a very good job.

minimaxon Show HN: 3D shooter in your terminal using raycasting in Awk

As in Javascript, awk represents all numeric values using double precision floating point. I have always thought that was a strange (but not necessarily bad) choice for a language that is basically all about text processing. I guess it works out pretty well if you need to do 3D graphics math.

There is a bit of cheating going on here though. Awk doesn't support true multidimensional arrays. They are depending on a Gawk extension for that bit of functionality.

minimaxon TIS-100P on the App Store

I really loved playing this game on Steam and I would happily pay for more levels. I wonder how useful TIS-100 would be for teaching programming. The limited instruction set and number of registers make for a very simple and easy to understand programming environment.

minimaxon The search for a faster CRC32

According to the Stephan Brumme website you linked to, the slice-by-8 lookup table is 8K and the slice-by-16 table is 16K, so your combo version of crc32 needs 24K of L1 cache to run at full speed. Modern server class CPUs typically have 32K of L1 dcache so that doesn't leave much room for the rest of your work. Maybe that's reasonable (I don't really know what Cyrus does), but I thought it was worth thinking about.

minimaxon The search for a faster CRC32

I read more about the slice-by-N algorithms because they sounded really interesting. The way they work is by using a set of lookup tables that are 4k to 16k in size (larger lookup table for larger N). The reason they are fast is because the lookup tables fit within the L1 cache on modern CPUs. So when you do 100M rounds of CRC32 it is super fast because the table is always cache hot, but I don't think this result is informative if you just want to occasionally do a CRC in between doing other types of work (especially for small buffer sizes). You will have to wait as the lookup tables are brought up through the cache heirarchy _and_ you are potentially evicting other useful data from the cache at the same time. Presumably PCLMULQDQ does not have this drawback.

minimaxon Tested: Why the iPad Pro really isn't as fast a laptop

I'm not sure this is a great article, but I went down the rabbit hole anyway and eventually landed on some pretty cogent thoughts from Linus Torvalds regarding flaws in the Geekbench benchmarking methodology.

http://www.realworldtech.com/forum/?threadid=136526&curposti...

minimaxon Hurricane LTE-U: Don’t Let Wi-Fi Get Blown Away

Meanwhile, Qualcomm, which is developing the technology, plied journalists with breakfast and lunch in an effort to convince them LTE-U was totally benign.

As much as I like the idea of a bunch of scheming Qualcomm executives sitting around a giant conference table plotting to ply journalists with breakfast and lunch, maybe it's possible they were just being polite hosts?

minimaxon Developing in Stockfighter with No Trading Experience

I'm not sure what exactly you mean by block (in terms of size), but let's say you have a stock and the average number of shares at the inside (best) price is X. If you are trying to trade 10X shares, you aren't just going to aggressively trade through multiple price levels all at once to get the trade done, and if you just place an order for 10X shares into the book you will find that the price starts moving away from your order price pretty quickly. For a high volume ETF like SPY, X can be thousands of shares, but for low volume mid/small caps it may be only a few hundred shares, which is not something I'd consider "incredibly liquid."

minimaxon Developing in Stockfighter with No Trading Experience

The stock market is incredibly liquid: for any stock listed on an exchange, you can buy almost any quantity and sell almost any quantity, at any time the market is in session.

I think that sentence would make most professional equities traders chuckle. I mean, it's true-ish for some of the big etfs and some of the highest volume individual companies, but there are 8k+ listed symbols in the US and you can't just go buying and selling "almost any quantity" of most of them. Nobody really trades that way. Trading in size typically involves chopping a large order into smaller orders that get managed by a trader or really a trader's execution algorithm.

minimaxon Homan Square, Chicago police's off-the-books interrogation warehouse

Here are some articles from the local Chicago press from the last time this came up:

http://www.wbez.org/news/chicago-polices-so-called-black-sit...

http://www.chicagotribune.com/news/local/breaking/ct-homan-s...

Not trying to defend CPD here, but the guardian seems to be alone in trying to dramatize this into a story about the Homan Square facility being sort of black ops detention facility.

minimaxon YC Continuity

Maybe I have misunderstood your comment, but my understanding is that any flaws that may exist in the market are relatively small problems relative to the issues arising from the increased regulatory requirements (Sarbanes Oxley, etc) for public companies.

minimaxon Twitter announces layoffs

Twitter filed a Form 8-K with the SEC this morning.

https://www.sec.gov/Archives/edgar/data/1418091/000156459015...

I'm not a securities lawyer, but I think the basic idea is that news about the layoffs (and the associated costs) was deemed to be material information, so under reg FD it has to be released to all investors simultaneously.

minimaxon Pilots who risk their lives flying tiny planes over the Atlantic

If you liked this article you'd probably also enjoy the book "Wind, Sand, and Stars" by Antoine de Saint-Exupery. It's all about his time flying as an airmail pilot through the Alps, over the Sahara, and crossing the South Atlantic in the early 20th century.

minimaxon Why Do High-Frequency Traders Cancel So Many Orders?

The NY/Chicago arb trade is futures vs equities. In other words it's two separate products with highly correlated prices. On one side are the futures contracts and on the other side are the underlying stocks (and ETFs). As long as the two separate products exist, you'll always have fast arbitrageurs. This is true whether the matching engines are 1000 miles apart or in the same rack.

minimaxon Ask the algorithm: Human wealth advisers are going out of fashion

I don't think I was making an argument about the cost of mutual funds vs ETFs, but claiming mutual funds are more expensive than ETFs is silly. There are high cost ETFs just like there are high cost mutual funds. You have to look at the expense ratios etc, etc...

minimaxon Ask the algorithm: Human wealth advisers are going out of fashion

A mutual fund manager is not the same as a private wealth manager. Robo-advisors are replacements for private wealth managers. For example, a robo-advisor could recommend a human-managed mutual fund, or a human wealth manager could recommend a low cost index fund. You are confused about the two roles.

minimaxon The 'Flash Boys' Exchange Is Growing Up

Some people (of which I'm one) don't have anything good to say about Flash Boys. On the other hand I don't think there are many people who have bad things to say about IEX or Brad Katsuyama. They are doing their thing and they'll succeed or fail based on their ability to compete with the other exchanges. It's hard to complain about that.

minimaxon The 'Flash Boys' Exchange Is Growing Up

This is actually a really interesting question. They would have to show size at the inside otherwise sweeping under Reg NMS would be impossible (you have no way of knowing how many shares to clear the protected quote). Also they already have a prop feed (IEX TOPS) that already shows size/price at the inside.

Under their proposed Rule 11.330, they only have two prop feeds which are the TOPS feed and a last sale feed. So no full depth feed. They would be the only US equities exchange without a full depth feed, but it looks like that's what they want to do.

minimaxon High Frequency Trading Defined

I think he is lumping dark pools in with exchanges. Technically there are only 11 registered US equity exchanges and any displayed quote has to be accessible to all market participants under nondiscriminatory terms.

Dark pools OTOH tend to have all sorts of gimmicks with respect to whose orders are allowed to match against other orders and under what circumstances. E.g. if I connect to a bank-run dark pool, I may be able to opt out of matching against principal flow from any of the bank's prop desks. The matching rules should be described in a dark pool's "form ATS" which some dark pools publish (and some don't).

minimaxon World Airports Voronoi

I recently did ORD-HKG and spent quite a lot of time thinking about ETOPS diversion airports over Siberia (because honestly what else are you gonna do). Now I'm wondering if you can even land a fully laden 777 at any of them. Most of them don't even seem to have wikipedia pages.

minimaxon Understanding ETF “Flash Crashes”

It doesn't matter. You don't have to trade the stock at its listing exchange.