Bufetico
At the start of September, an office worker who lives in Yeouido, in Seoul, saw a window pop up on his screen and vanish, the one that shows what buyers and sellers are offering for an American fund. He suspected a bug. It only made sense once he checked the notices on his broker’s website, the Korean outlet Newspim reported.
The fund was SOXL, which aims to move three times as much as an index of chip stocks each day. In Korea it goes by a nickname, ssokseul, and at the end of August investors there owned 27 percent of it, by the Korea Herald’s math on figures from Korea’s securities depository. Their brokers let them trade American stocks during the day through Blue Ocean, a US trading venue that stays open overnight in New York, 8 p.m. to 4 a.m. In the summer that’s 9 a.m. to 5 p.m. in Seoul.
The arrangement had broken before. On a day of heavy selling in August 2024, Blue Ocean canceled trades on about 90,000 Korean accounts, and the brokers shut the service down for more than a year. When they brought it back last November, they signed up two backup venues, MOON and Bruce, to keep it from happening again.
On September 1, Blue Ocean stopped trading SOXL and 17 other securities, most of them funds that multiply or flip a day’s move. It said it was following an SEC rule on fair access. Once a venue like that handles 5 percent or more of the trading in a stock or a fund, four months out of six, it takes on extra duties, like written, objective rules for who gets to trade there.
Halting a stock or a fund was Blue Ocean’s own way of staying under that line, and it had been halting more and more of them, Edaily, another Korean outlet, reported later. Korean investors, the same report said, were about 35 percent of Blue Ocean’s trading. The halts lasted until September 10, New York time.
The backups took the orders. They just didn’t send live quotes to Korean platforms, so for those ten days people placed limit orders, orders with a price they won’t go past, without seeing what buyers and sellers were offering at that moment. People in the market called it blind trading, the Korea Herald reported, and a brokerage official told the paper that trades could still go through “based on the last available price.”
What was left on the screen
On a quote, that’s the last price: the price of the most recent trade. It isn’t necessarily what a market order gets, an order to trade right away at whatever price is there. Next to it sits the change, how far the price has moved since the previous close. The volume is how many shares changed hands, so it tells you how much trading stands behind the number. Even the close depends on who’s showing it: some data vendors count the last after-hours trade as the close, and others go with the 4 p.m. price.
What vanished from those Korean screens was the bid and the ask. The bid is the most a buyer will pay at that moment and the ask is the least a seller will take, and the gap between them is the spread. Both hold only for a set number of shares, so the price on your screen isn’t always the price you get. Without them, you’re setting a limit without knowing where the market is.
Which hours
Regular trading hours on US exchanges run from 9:30 a.m. to 4 p.m. Eastern time. In September that’s 10:30 at night to 5 in the morning in Seoul, so the whole Korean workday falls outside them. The rest of the time there’s less interest in trading, and the SEC says that usually means wider spreads between the bid and the ask, or no quotes at all.
The overnight session, where those Korean daytime orders go, is a thin market. In August it was 0.9 percent of all the shares traded in listed US stocks on an average day, the SEC’s staff counted. The public feed that collects the market’s trades and quotes doesn’t even run overnight yet.
So I read a quote backwards now, and the price goes last. Before it, I want to know when that number last changed and whether anything traded. The time and the date get me started, and the volume tells me if any shares changed hands. After that, I look at where the trade happened and in what money.
Which day
The date is where my own screener went wrong. PetroChina, which traded in New York as PTR, left the New York Stock Exchange on September 8, 2022, and kept trading in Hong Kong and Shanghai. At the end of August this year my screener still had a price for PTR, stored with a date two days old, and my records hadn’t seen a new closing price for it in almost four years. It’s the problem of dead listings that still carry a price, and a fresh date is what hid it.
My screener says so now. A price that’s stopped moving gets a red line saying there’s been no price since a given month, and for PTR that’s September 2022. That line ignores the stored date and goes by my own records: the last week a new closing price came in, or the last week the price changed. A price that’s old but not dead shows its date in amber next to the currency, and one from before a weekend or a short holiday gets no label. On Monday, September 7, in the middle of those ten days, the NYSE was closed for Labor Day, and a New York quote with Friday’s date was right.
Where this breaks
A small company that trades very little can sit at the same price for weeks and get the red line while it’s alive, and on a day with no trades at all, its price and volume look just like a dead one’s. The amber line is pretty blunt too: a price several days old in a normal week is already stale, and the app won’t say a word.
Reading carefully also can’t show you a quote your screen doesn’t have. Back in 2008 the SEC warned that some firms, after hours, only let investors see quotes from the single system they trade through. That’s where the Korean platforms were at the start of September, and a time stamp won’t tell you how many venues stand behind the number.
The notice in Yeouido
The office worker in Yeouido got his answer from a notice on his broker’s website. Newspim spelled out the part a quote screen has no room for: SOXL itself wasn’t halted. Only Blue Ocean stopped trading it, and in New York’s premarket and regular session, Seoul’s evening and night, it traded as before.
Korean investors kept at it. Edaily compared the depository’s numbers: from September 1 to 10, Korean trading in SOXL came in about 60 percent above what it was from August 21 to 31, and each stretch held seven trading days in New York. The paper put it down to trading in New York’s regular session and other hours. In Seoul, the price had just moved to the night shift.