USD/JPY and the Bank of Japan

USD/JPY is the second most-traded currency pair globally, accounting for roughly 13-14% of daily FX turnover in the latest BIS Triennial Survey. It is also the most policy-driven major pair on earth: most of its directional movement traces back to the gap between Federal Reserve policy and Bank of Japan policy, which has been one of the largest cross-country policy divergences in modern monetary history for the better part of two decades. Understanding USD/JPY without understanding the BOJ is impossible.

This article walks the pair: the quote conventions (which differ from every European major), the long history of BOJ policy regimes that shaped the modern yen, why USD/JPY tracks US real yields more closely than any other pair, the carry-trade dimension, the MOF intervention history, and the practical pattern.

The quote and the pip convention

USD/JPY is the dollar against the yen. The dollar is base; the yen is quote. USD/JPY = 156.20 reads: one US dollar is worth 156.20 Japanese yen. The base-currency arrangement is the reverse of EUR/USD and GBP/USD (where the dollar is the quote). When USD/JPY rises, the dollar is strengthening against the yen.

The pip convention is also different. Yen pairs are quoted to two decimal places rather than four, because a single yen is a small unit. A pip is the second decimal of the quote: a move from 156.20 to 156.21 is one pip. (Fractional pips, sometimes called pipettes, are the third decimal, displayed by most brokers but representing 0.1 of a pip.)

Pip value requires one extra step because the quote currency is not the dollar. The pip value in yen is ¥1,000 per standard lot, ¥100 per mini lot, ¥10 per micro lot. Converted at a 156 exchange rate, that is approximately $6.41 per pip per standard lot, $0.64 per mini, $0.064 per micro. Pip value in USD changes slightly as the exchange rate moves, so the platform calculates it for you.

The convention is to call the pair “Dollar-Yen” or just “Yen” in trading-floor language, despite the dollar being the base. The two informal nicknames are “Ninja” (newer, common online) and “Gopher” (older, almost extinct).

The BOJ policy regime, in brief

The Bank of Japan has spent most of the 21st century at the global zero-rate frontier. A condensed history:

• 1999-2000. BOJ becomes the first major central bank to adopt a near-zero policy rate (0.25%, then 0.10%) in response to the post-bubble lost decade.
• 2001-2006. Quantitative Easing (the original): the BOJ pioneered large-scale asset purchases as a policy tool, before the term was familiar to Western markets.
• 2008-2012. The global financial crisis and the Tohoku earthquake push the BOJ back to deeper QE.
• 2013. Governor Haruhiko Kuroda introduces Quantitative and Qualitative Easing (QQE): aggressive balance-sheet expansion with a stated 2% inflation target.
• 2016. Yield Curve Control (YCC): BOJ caps the 10-year JGB yield at 0%, then later at 0.25% and 0.50%. The policy is unique among major central banks.
• 2024. BOJ exits negative rates and abandons YCC under Governor Kazuo Ueda, raising rates to 0.25% in July 2024 and to 0.50% in early 2025. The first meaningful rate hike since 2007. The yen begins to recover from multi-decade lows.

The structural fact behind all of this: for the better part of 25 years, the Bank of Japan has run the loosest monetary policy of any major central bank, and Japanese government bond yields have been the lowest in the developed world. This has made the yen the world’s primary funding currency, because it is structurally cheap to borrow. Borrow yen, sell yen, buy something else with higher yield. The carry trade is the universal name for this pattern.

Why USD/JPY tracks US real yields

The single tightest statistical relationship in major-pair FX is between USD/JPY and the US 10-year real yield (the nominal yield minus expected inflation). The correlation typically runs above +0.7 and often above +0.9. The reason is the funding-currency logic above.

When US real yields rise, the gap between yields available in dollars and yields available in yen widens. Borrowing yen to buy dollars becomes more attractive. Capital flows out of yen and into dollars. USD/JPY rises. When US real yields fall, the gap narrows, the trade unwinds, USD/JPY falls.

The relationship is asymmetric in one important way: it tightens during yen-weakness episodes and breaks during yen-strength shocks. When risk-off panic hits and the carry trade unwinds en masse, USD/JPY can fall sharply even with US yields still elevated. The unwinding flow overwhelms the yield-differential logic for hours or days at a time. The classic example is the August 2024 episode in which an unexpected BOJ rate move triggered a global carry-trade unwind and USD/JPY moved from above 161 to under 142 in a few weeks.

What else drives USD/JPY

The yield story dominates, but other drivers matter:

• The DXY overlay. The yen is 13.6% of the Dollar Index, the second-largest weight after the euro. Broad dollar moves register in USD/JPY just as they do in every USD pair.
• The risk-on / risk-off regime. The yen is a classical safe haven, alongside the dollar and the franc. In flight-to-safety episodes, the yen often strengthens against everything, including the dollar, pulling USD/JPY lower.
• BOJ policy meetings and minutes. Eight meetings per year. With YCC abandoned and BOJ now in a tightening cycle for the first time in a generation, these have become high-impact events in a way they were not for most of the 2010s.
• Japanese inflation data. Core CPI excluding fresh food is the BOJ’s policy focus. A sustained move above 2% has been the prerequisite for BOJ tightening.
• Ministry of Finance intervention threats. The Japanese MOF (not the BOJ) has authority over yen intervention. When USD/JPY moves too quickly toward levels the MOF considers excessive, verbal warnings precede actual intervention. The MOF intervened directly in markets in October 2022 and again in 2024, each time briefly stalling sharp yen weakness. Traders pay attention to MOF rhetoric, particularly above 155.

Sessions and the yen-pair time of day

USD/JPY is the only major where Asian session liquidity is genuinely deep. Tokyo is the home market.

• Tokyo session (00:00-09:00 GMT). Active, not quiet like other majors. Japanese corporate flow concentrates in the early Tokyo morning. BOJ announcements typically hit around 03:00-04:00 GMT. Spreads are competitive.
• London open (08:00 GMT). European participation adds liquidity; the EUR/JPY cross gets active, with knock-on effects on USD/JPY.
• London-New York overlap (13:00-17:00 GMT). Deepest window. US data hits here. US yield moves on releases like CPI and Non-Farm Payrolls produce the largest single USD/JPY moves of the typical trading day.
• New York afternoon (17:00-22:00 GMT). Active until the Tokyo open the following day. Less of a dead zone than for EUR/USD.

The practical implication: USD/JPY is the only major where trading the Asian session is a reasonable choice, particularly around BOJ days and Japanese data prints.

The carry trade and the swap dimension

A long-USD/JPY position is structurally a long-carry trade: long the higher-yielding currency, short the lower-yielding one. Even in 2025 with BOJ in tightening mode, the gap between Fed funds and BOJ rates is still 4 percentage points or more. The position receives swap on the long side every night.

This sounds like free money. In normal conditions, it is small, positive, and steady. The catch is the tail. The yen tends to appreciate violently in crises, exactly when carry-trade unwinding is forced by margin calls and risk-reduction at funds and CTAs. The skewness of carry-trade returns is sharply negative: many small positive nights, occasional very large negative days. This pattern is well-documented in academic FX literature, and it is the central reason the carry trade is not the obvious-good-idea it appears to be on paper. (A planned Phase D piece will treat the carry-trade tail-risk dynamic in depth.)

For a retail trader, the practical implication is that “long USD/JPY for the swap” is a strategy with positive expected return in calm regimes and ruinous left-tail exposure in crisis regimes. The position should be sized accordingly, not as a quasi-deposit.

Correlations

USD/JPY’s correlation web is distinctive:

• Strongly positive with US 10Y real yield. The headline relationship. See above.
• Variable with DXY. Positive on yield-driven days, less so on risk-driven days. A DXY rally led by US-yield strength pulls USD/JPY higher with it; a DXY rally driven by global risk-off pulls USD/JPY lower because yen-haven flow dominates.
• Negative with global equities in crisis, positive in calm. The same risk-regime split as DXY.
• Strongly positive with EUR/JPY and GBP/JPY. All three yen crosses share the yen-weakness or yen-strength signal. EUR/JPY and GBP/JPY are essentially USD/JPY × the corresponding non-USD pair, so the relationship is partly arithmetic.
• Variable with EUR/USD. Often near zero, sometimes meaningfully positive, sometimes negative. The two USD pairs are driven by different ratios of common factors (yields, risk).

Sizing and the yen-pip catch

One trap for new yen-pair traders: pips are the second decimal, not the fourth. A “20-pip stop” on USD/JPY is a 0.20-yen distance, not 0.0020. The sizing arithmetic in Risk Management Basics uses the correct pip value automatically, but the mental conversion catches people. A trader used to four-decimal pairs sometimes accidentally sizes a yen-pair position ten times larger than intended because they treated the stop distance as 0.0020 (fourth decimal) instead of 0.20 (second decimal).

The same mental conversion applies to spreads: a “2-pip spread” on USD/JPY is 0.02 yen, on EUR/USD it is 0.0002. Same word, different unit.

The honest tradability note

USD/JPY is uniquely policy-readable: the yield-differential story gives a clear macro overlay that most other pairs lack. It is also uniquely exposed to regime change, because the carry-trade dynamic that powers most of its directional moves is structurally asymmetric.

Realistic expectations:

• Macro-readable but not predictable. Knowing that USD/JPY tracks US yields does not tell you what US yields will do next.
• Spread is competitive, swap matters. Spreads of 1.0-1.5 pips on USD/JPY are normal. Swap on a long-USD/JPY position is small per night but compounds; on a short, it works the other way.
• Tail risk is real and recurring. The carry-trade unwinds of August 2007, October 2008, August 2015, March 2020, and August 2024 all moved USD/JPY by multiple standard deviations in days. An account sized for normal conditions will not survive one without a meaningful drawdown.
• MOF risk is unique to this pair. Direct intervention is rare but not theoretical. Verbal interventions can move the pair 100 pips on a single comment.

The takeaway

USD/JPY is the dollar against the yen, quoted to two decimals with the pip at the second decimal. It is dominated by the relative path of Fed and BOJ policy and by the US 10-year real yield. The yen is the world’s primary funding currency, which makes USD/JPY a carry-trade vehicle with positive expected return in calm regimes and sharply negative skewness in crisis regimes. The Bank of Japan exited its long zero-rate experiment in 2024; for the first time in a generation, BOJ days move the pair on their own merits.

For the macro context, read The Dollar Index (DXY). For the companion pairs, read EUR/USD: The Fibre and GBP/USD: Cable. For the sizing discipline the yen pairs really require, particularly given carry-trade tail risk, read Risk Management Basics and Currency Correlation and Hidden Risk.