Japan's Margin Trading Data: What It Says About Kioxia

Margin trading (信用取引, shin’yō torihiki) is trading with cash or shares borrowed from a broker. The “margin balance” is the amount of those loans not yet repaid. The Tokyo Stock Exchange (TSE) counts it from two sides: borrowed cash used to purchase shares (long margin positions) and borrowed shares put on the market (short margin positions). Since September 28, 2026, TSE posts both figures for every listed issue each business day. For Kioxia Holdings (285A), its files show 46,825,200 shares on the long side and 1,869,900 on the short side as of October 19, 2026.

All figures below come from TSE files on the Japan Exchange Group (JPX) website. They are counts of shares and yen amounts, not prices.

What is margin trading in Japan?

JPX defines a margin transaction as one that uses funds or securities a customer has borrowed from a securities company after depositing collateral. The deposit must be at least 30% of the trade’s value, with a minimum of ¥300,000, so a customer can trade up to about three times the deposit. If losses cut the deposit below 20% of the trade’s value, the broker asks for more. The position is closed later, usually by an offsetting trade.

There are two kinds, and the customer picks one when placing the order:

	Standardized (制度信用)	Negotiable (一般信用)
Eligible issues	Selected by TSE	In principle, all listed issues
Repayment deadline	Up to six months	Set between customer and broker
Premium charge	Announced by TSE	Set between customer and broker
Loans from a securities finance company	Available	Not available

For standardized trades, brokers can borrow the cash or shares they lend from Japan Securities Finance Co. (JSF), which TSE has designated for this role. When JSF runs short of shares to lend, it borrows them at auction; the resulting fee, the premium charge, is paid by every standardized short position in that issue and received by every standardized long one.

Individuals dominate this market. TSE’s own overview says individuals accounted for 96% of brokered margin trading on the Prime Market in 2025, by value, and that 75% of individuals’ trading there was on margin.

What do the two balances mean?

JPX’s glossary defines the two balances (信用取引残高) as the cash borrowed for purchases and the shares borrowed for sales that have not yet been repaid. In TSE’s English files the columns are named “Outstanding Purchases” (買残高, kai-zandaka) and “Outstanding Sales” (売残高, uri-zandaka). Below, these are the long and short margin positions.

For each side, the file shows the total, its change from the previous day, the total as a share of listed shares, and the split between standardized and negotiable positions. Since the September 2026 change, each issue also has a yen amount. TSE’s weekly market-wide table says its yen totals are at contract prices; the per-issue file does not state a basis.

The margin ratio (信用倍率, shin’yō bairitsu) is not in the TSE file. It is derived: the long balance divided by the short balance, in shares, as SMBC Nikko Securities defines it. JPX publishes a different statistic called the “Margin Trading Ratio” (信用取引売買比率): the share of a day’s trading volume made up of new margin trades, posted for a short list of issues, mostly those under daily publication or restrictions. Kioxia was not in the October 20 edition.

Who publishes the data, and when?

Publication	Publisher	Covers	When (Tokyo time)
Outstanding Margin Trading by Issue	TSE	Every listed issue, previous trading day	About 16:00, every business day
Current Outstanding Margin Trading	TSE	Market-wide totals (TSE and Nagoya), previous week’s last business day	About 16:00, second business day of the week (usually Tuesday)
Issues Subject to Daily Publication	TSE	Issues TSE or JSF have flagged	About 16:00, every business day
Loans for margin transactions, by issue	JSF	JSF’s share and cash lending	Preliminary about 19:00; final about 23:00

The per-issue data used to be weekly. Until September 2026, TSE posted balances by issue on Tuesdays at about 16:30 for the previous week’s last business day. In a notice of December 15, 2025, TSE said a system replacement would move all issues to daily publication and add yen amounts. A second notice set the change for September 28, 2026: the last weekly file covered September 18, and the first daily file covered September 25.

So the October 19 balances appeared on October 20 at about 16:00 in Tokyo (15:00 in Singapore). JPX labels each file “application based,” dated by the trading day. Its page lists only the latest five files.

TSE says designating an issue for daily publication is meant to alert investors about margin use and is not a regulatory measure. When it deems margin use excessive, it can impose restrictions; its example of a first stage is a 50% deposit, including 20% in cash. Kioxia was neither on the daily-publication list nor under margin restrictions on October 20.

JSF’s per-issue lending figures cover only standardized trades that go through JSF. Its English site points to a search tool whose results are in Japanese.

What do TSE’s files show for Kioxia?

Kioxia appears in TSE’s files as a Prime Market “Loan” issue (貸借銘柄), one of the issues TSE has selected for standardized margin trading. These are its balances in shares:

As of (2026)	Long (shares)	Short (shares)	Long ÷ short
Oct 1	41,594,900	2,597,400	16.01
Oct 9	44,798,300	1,503,400	29.80
Oct 13	49,502,600	913,900	54.17
Oct 14	49,686,400	1,400,800	35.47
Oct 15	48,805,000	1,283,100	38.04
Oct 16	47,831,100	1,536,300	31.13
Oct 19	46,825,200	1,869,900	25.04

The October 1 and October 9 rows come from archived copies of the TSE files, since JPX’s page now lists only the five latest. The long side rose 12.6% from October 1 to October 19, peaking on October 14 in these files. The October 19 long balance equaled 2.8% of Kioxia’s listed shares; the short balance, 0.1%. Of the long balance, 29,564,800 shares (63.1%) were standardized, the kind with a six-month deadline, and 17,260,400 negotiable.

The yen amounts tell the same story. On October 15, the long side carried ¥920.9 billion. Seoul Economic Daily, citing a Bloomberg report based on TSE data, put the figure at about ¥920 billion for that date, the largest of any TSE-listed company. In the October 19 file, the figure was ¥880.9 billion. No other issue showed a larger amount; it was about 13% of the ¥6.63 trillion total for all 4,249 issues in the file.

These are counts of open positions. They show how much borrowed money and borrowed stock sit in the shares on a given day. They do not show who holds the positions, at what prices they were opened, or what happens next.

Does the 3-for-1 split change the numbers?

Yes, for share counts. Kioxia split each share into three, with a record date of September 30, 2026, effective October 1. Every row in the table is dated October 1 or later, so all are on the post-split basis. A balance in shares from a file before the split, such as a weekly file from early September, counts old shares: multiply it by 3 to compare. The yen amounts and the long-to-short ratio do not need adjusting. Our guide to Kioxia’s split explains how to put prices on one basis.

Where can I check the latest figures?

The English page “Outstanding Margin Trading by Issue” on jpx.co.jp has a PDF for each of the last five trading days. Kioxia sits in code order under 285A0, with a share row and a yen row. The weekly market-wide totals are on the page “Current Outstanding Margin Trading,” and JSF’s lending data is on taisyaku.jp. To see how Kioxia’s price moved against other Japanese chip stocks over the same days, open the Japan map.