Call market structure

Wiki route

This entry sits under money-market index. Read it against Japan money market for peer / contrast context and BoJ open market operations for the broader system / regulatory boundary.

TL;DR

The call market is Japan’s short-term interbank funding market. The uncollateralized overnight call rate is especially important because it is the policy-rate transmission point used in BoJ money-market operation guidelines. Banks and other financial institutions use overnight call transactions to adjust end-of-day liquidity; tanshi companies sit in the market as brokers / intermediaries.

Use this page when interpreting short-rate normalization, tanshi-company relevance, or the difference between the BoJ’s operating guideline and the actual traded overnight rate.

Core Mechanics

Element	Explanation
Transaction	Very short-term lending / borrowing, especially overnight.
Uncollateralized O/N call rate	The headline short money-market rate that BoJ policy guidelines have historically targeted.
Participants	Banks, trust banks, securities firms, other eligible financial institutions, and money-market brokers.
Tanshi role	Tanshi companies intermediate short-term funds and provide market-function infrastructure.
Data source	BoJ publishes provisional and final Call Money Market Data on business days.

How To Read The Rate

Do not read the call rate as a simple deposit rate. It is a wholesale money-market price shaped by:

the BoJ’s policy guideline;
current-account balances and reserve conditions;
participant access to BoJ accounts;
collateral and repo alternatives;
quarter-end / fiscal-year-end liquidity demand;
counterparty limits and balance-sheet constraints.

Uncollateralized vs collateralized segments

The call market historically had two segments distinguished by whether the loan is backed by collateral. In current practice “the call rate” means the uncollateralized overnight rate; the collateralized segment is largely a historical and definitional contrast.

Dimension	Uncollateralized call (無担保コール)	Collateralized call (有担保コール)
Security	Unsecured; pure counterparty credit exposure.	Secured against pledged eligible collateral.
Credit risk borne by lender	Full counterparty credit risk.	Mitigated by collateral.
Headline rate	Uncollateralized overnight call rate — BoJ operating target.	Collateralized call rate — not calculated since April 2016 (no tanshi-intermediated trades).
Current activity	Active, though volumes vary with the reserve environment.	Effectively dormant as a brokered segment.
Tenors	Overnight dominant; term transactions also occur.	Historically overnight and term.
Why used	End-of-day reserve / settlement adjustment, securities-firm inventory funding.	Older secured-funding channel before repo growth.
Data	BoJ Call Money Market Data, updated each business day.	No current rate series published.

The collateralized call rate has not been calculated since April 2016, because there have been no transactions intermediated by tanshi companies; the BoJ computes the volume-weighted average call rate from actual tanshi-reported transactions, so a segment with no such trades has no published rate.

Why the uncollateralized segment dominates:

Operating-target gravity: because BoJ guidelines reference the uncollateralized overnight call rate, it is the rate both participants and the central bank watch, concentrating liquidity and price discovery there.
Repo absorbed secured funding: secured short-term funding migrated into the JGB repo market (GC / SC repo and cash-collateralized securities lending), which has deeper infrastructure and a clearer collateral-management framework than the old collateralized call channel.
Participant mix: banks adjust reserve / settlement balances and securities firms fund inventory in the uncollateralized call market; securities firms in particular stay incentivized to do term uncollateralized call transactions to finance inventory and manage the Liquidity Coverage Ratio.

The result is a market where the unsecured segment carries the policy-relevant price and the secured short-term funding role sits in repo, leaving the collateralized call segment as a definitional contrast more than a live market.

Relationship to other front-end markets

Market	How it relates to the call market
[[money-market/jgb-repo-market-japan	JGB repo]]
[[derivatives/ois-tona-curve	TONA / OIS]]
[[money-market/japan-tibor-benchmark-rate	TIBOR]]
[[money-market/japan-ncd-negotiable-cd-market	NCD]] and [[money-market/japan-cp-commercial-paper-market

Reading checklist

When a source says “the call rate,” confirm it means the uncollateralized overnight rate unless explicitly stated otherwise.
Do not expect a current collateralized call rate; it has not been calculated since April 2016.
Route secured short-term funding questions to repo, not the collateralized call segment.
Separate the operating-target rate (uncollateralized overnight call) from term call transactions and from secured funding.
Read call-market activity against the reserve environment and BoJ operations rather than as a standalone signal.

JapanFG Relevance

tokyo-tanshi, central-tanshi, and ueda-yagi-tanshi are the direct tanshi-company route.
mufg, smfg, and mizuho-fg are affected through short-rate transmission, reserve balances, and wholesale funding.
mizuho-securities, mufg-mums, and other securities firms are affected through repo, JGB collateral, and dealer balance sheets.
boj-monetary-policy sets the policy framework; this page explains the market surface.

Boundary Cases

Call market vs repo market: uncollateralized call lending is not the same as secured repo or JGS lending.
Policy target vs actual rate: the BoJ can encourage the O/N call rate around a target, but the actual rate is still a market statistic.
Tanshi company vs bank: tanshi companies are market intermediaries, not deposit-taking banks in the ordinary retail sense.
Collateralized call vs repo: both are secured, but repo is a securities-financing transaction with a repurchase commitment, while collateralized call is secured lending pledging collateral; the two are not the same legal structure.
Uncollateralized call vs interbank deposit: bilateral interbank deposits are economically related but are not the brokered call-market transactions that feed the published call rate.
Term call vs overnight call: term uncollateralized call transactions exist, but the policy-relevant headline is the overnight rate.

Sources

Bank of Japan: Call Money Market Data.
Bank of Japan: How have the Bank’s guidelines for market operations changed?
Bank of Japan: What are market operations?
Bank of Japan: framework paper explaining the money-market adjustment role of the uncollateralized overnight call market.
Bank of Japan: explanation of “Statistics on Call Money Market,” including the note that the collateralized call rate has not been calculated since April 2016 due to absence of tanshi-intermediated transactions.
Bank of Japan Review (2024): developments in Japanese money markets, including securities-firm incentives for term uncollateralized call transactions.