Theory

The Yen Glitch — Full Methodology

1 Mar 202612 min read

Overview

The YEN CARRY score is a composite of seven independently sourced signals that together estimate the probability and proximity of a yen carry trade unwind event. Each signal is normalized to a 0–100 scale, weighted, and summed to produce a final score.

The score updates every 15 minutes during market hours.

Score interpretation

| Score | Status | Interpretation | |-------|--------|---------------| | 0–20 | NORMAL | Carry trade intact, no unwind signals | | 21–40 | WATCH | Weak signals, increased monitoring | | 41–64 | ELEVATED | Multiple signals active, watch closely | | 65–79 | CAUTION | Unwind likely, consider positions | | 80–100 | DANGER | Unwind in progress, execute strategy |

Signal architecture

The seven signals and their weights in the composite score:

| Signal | Source | Weight | |--------|--------|--------| | USD/JPY spot level | Yahoo Finance | 25% | | COT positioning | CFTC (weekly) | 20% | | Tokyo CPI | e-Stat Japan | 15% | | Swap spread | FRED / Yahoo Finance | 15% | | JPY implied volatility | Yahoo Finance (VXJ) | 10% | | Nikkei vs SPX | Yahoo Finance | 10% | | FXY ETF flows | Yahoo Finance | 5% |

Signal 1: USD/JPY spot level (25%)

Source: Yahoo Finance (real-time) Threshold: 145.00 Score formula: max(0, min(100, (rate - 130) / (165 - 130) * 100))

The USD/JPY rate is the most direct measure of yen carry trade positioning. A high rate means the yen is weak, carry trades are on, and the potential energy for a reversal is large.

The signal activates at 145.00 (our baseline threshold) and reaches maximum score at 165.00. Below 130.00, the score is zero — at that level, carry trades have already unwound significantly.

Backtested note: The August 2024 unwind began with USD/JPY at 157.8. Our threshold was passed in April 2024, providing 15 weeks of lead time.

Signal 2: COT positioning (20%)

Source: CFTC Commitments of Traders report (released Fridays, data as of Tuesday) Threshold: Net short JPY speculative position > 50th percentile of 2-year rolling window Score formula: Percentile rank of current net position over 104-week lookback

The CFTC COT report shows futures positioning by category (commercial hedgers, non-commercial speculators, small traders). The non-commercial short JPY position is our primary variable.

When speculative short positioning is extreme relative to history, it means:

  1. The trade is overcrowded
  2. Many participants are levered on the same side
  3. A trigger event will cause simultaneous exit, amplifying the move

Current data lag: 3 business days. We account for this in the signal weight — it's directionally correct but not precise for timing.

Signal 3: Tokyo CPI (15%)

Source: e-Stat Japan (Statistics Bureau of Japan) Threshold: Core CPI YoY > 2.5% and accelerating Score formula: Weighted composite of headline, core, and services CPI components

Tokyo CPI is published roughly 2–3 weeks before national CPI and is the primary forward indicator for BOJ policy shifts. An accelerating Tokyo core CPI creates pressure on the BOJ to raise rates.

Higher BOJ rates → yen strengthens → carry trade unwind.

Why it matters: The August 2024 BOJ rate hike was preceded by Tokyo CPI running above 2.5% for 8 consecutive months. Traders who were watching dismissed it as "transitory." It wasn't.

Data source note: We use the e-Stat Japan API (Statistics Bureau) for official data, cross-referenced against Bloomberg consensus estimates when available.

Signal 4: Swap spread (15%)

Source: FRED (Federal Reserve Economic Data) and Yahoo Finance Threshold: JPY/USD 2-year interest rate swap spread > 4.0 percentage points Score formula: Linear scaling from 3.5pp (score 0) to 5.5pp (score 100)

The interest rate swap spread between JPY and USD captures the cost of running the carry trade. A very wide spread makes the trade attractive — and signals it is heavily on. When spreads are at extremes, the reversal can be equally extreme.

Signal 5: JPY implied volatility (10%)

Source: Yahoo Finance (^JNIV or VXJ equivalent) Threshold: 1-month JPY/USD implied vol > 10% Score formula: Linear scaling from 8% (score 0) to 20% (score 100)

Rising JPY implied volatility signals that options traders are pricing in larger USD/JPY moves. This is both a coincident and slightly leading indicator: options desks often accumulate protection before the spot market moves.

Note: This signal has the highest false-positive rate in our backtest. We weight it at 10% rather than higher for this reason.

Signal 6: Nikkei vs SPX underperformance (10%)

Source: Yahoo Finance (^N225, ^GSPC) Threshold: Nikkei 20-day return minus SPX 20-day return < −5% Score formula: Based on rolling 20-day relative return z-score

Japanese equities are deeply intertwined with the carry trade. When carry traders unwind USD/JPY positions, they also sell Nikkei-correlated assets. Persistent Nikkei underperformance relative to the S&P 500 signals that risk is being taken off in Japan specifically.

Signal 7: FXY ETF flows (5%)

Source: Yahoo Finance (FXY) Threshold: FXY 30-day return and volume divergence Score formula: Proprietary; based on price momentum and volume analysis

FXY (Invesco CurrencyShares Japanese Yen Trust) is a retail and institutional vehicle for yen exposure. Large inflows with rising price signal yen buying pressure — potential carry unwind. We weight this signal lightly (5%) due to lag and noise.

Composite construction

The final score is the weighted sum of individual signal scores, capped at 0–100:

score = Σ(signal_i × weight_i)
      = 0.25 × usdjpy
      + 0.20 × cot
      + 0.15 × tokyo_cpi
      + 0.15 × swap_spread
      + 0.10 × jpy_vol
      + 0.10 × nikkei
      + 0.05 × etf_flows

Each signal is computed independently and can be examined in the full dashboard.

Backtested performance (2019–2024)

The composite score crossed 65 (CAUTION) before each of the three major yen carry unwind events in our test period:

| Event | First CAUTION | Event date | Lead time | |-------|--------------|------------|-----------| | COVID crash (Mar 2020) | Feb 24, 2020 | Mar 9, 2020 | 14 days | | Rate shock (Oct 2022) | Oct 1, 2022 | Oct 12, 2022 | 11 days | | Carry unwind (Aug 2024) | Jul 3, 2024 | Aug 5, 2024 | 33 days |

False positives (CAUTION triggered but no major unwind): 4 instances over 5 years, with the score reverting below 65 within 2–3 weeks.

Methodology is reviewed quarterly. Last update: March 2026. For questions or corrections, use the contact form.