A plain-English guide to month-end FX rebalancing flows.

Today's Monday August 31 tape delivered the standard month-end footprint: a small directional flow through the London morning, a compressed range between 12:00 and 3:00 PM London, and a burst of EUR-buying against dollar in the 3:00 to 4:00 PM London window that produced the intraday DXY fade the Monday analysis piece attributed to the rebalance. That is the fingerprint of a specific set of flows that run every month and produce the recognisable shape. This piece is the framework: what the flows are, why they run when they do, how to identify them on the tape, and how they interact with a directional macro flow that is running the other way.

The four sub-flows

Month-end rebalancing is not one flow. It is a stack of four that arrive on different timelines and originate with different account types. They add up (or partially cancel) in the last two hours before the WMR 4:00 PM London fix, which is the observation window where the aggregate footprint is measurable.

1. Equity-side rebalancing. Global equity managers who target a hedged benchmark (MSCI ACWI, MSCI World, or a policy-based currency-hedged portfolio) rebalance their currency hedges to match the month-end value of their equity holdings. If US equities outperformed foreign equities during the month, the dollar-hedged equity position needs less dollar hedge (equity value has grown, so the dollar amount of the hedge stays the same but its relative size versus the equity has fallen); the rebalance buys back the sold-dollar hedge, which sells dollars against EUR, JPY, GBP. If US equities underperformed, the rebalance sells dollars into the fix again. The direction depends on relative performance; the magnitude scales with the outperformance gap.
2. Bond-side rebalancing. Similar mechanics for bond managers, especially the passive index-tracking bond funds. A currency-hedged foreign-bond portfolio has hedge ratios that need to be updated for month-end asset values. The direction depends on relative bond performance and hedge ratios; the magnitude is typically smaller than the equity-side rebalance because bond volatility is lower.
3. Sovereign wealth fund and central-bank reserve rebalancing. The larger sovereign funds and central banks that target constant currency weights rebalance monthly or quarterly. These flows are less predictable than the equity-side flow because they are driven by policy and are frequently opaque. The signature is a persistent 20-40 pip directional flow through a two-hour window with unusual size at the top of book.
4. Corporate-treasury dividend and coupon flows. US corporates paying dividends to foreign holders and foreign corporates paying dividends to US holders both produce month-end flows. Coupon payments on US Treasury and corporate bonds held by foreign accounts produce a similar footprint. The direction depends on the relative size of the flows; the magnitude is small on a monthly basis but concentrated in the last two days of the month.

The standard timing

All four sub-flows converge on the WMR 4:00 PM London fix as the standard execution window. This is not the only fix that gets used (some accounts execute at the London 12:00 PM fix, the ECB 2:15 PM fix, or the NY 10:00 AM CME fix), but the 4:00 PM London fix is the deepest and the one the aggregate rebalance flow prices against. The mechanics of the fix (a five-minute window during which the average price is computed as the fix rate) mean the buy-side flow can be executed at the fix rate rather than at the arrival price; the sell-side accepts the flow because the fix's tight time window limits the fill risk.

The observable pattern on the tape is a build-up of directional flow in the 3:00-3:55 PM London window (accounts positioning ahead of the fix), a burst of volume in the 3:55-4:05 PM London window (the fix itself), and a partial unwind in the 4:05-4:30 PM London window (as accounts that traded through the fix unwind their hedges). On today's Aug 31 tape, the EUR/USD move from 1.1595 at 3:00 PM London to 1.1618 at 4:05 PM London to 1.1612 at 4:30 PM London delivered exactly that footprint.

What direction the flow leans in any given month

The default direction of the month-end rebalance flow depends on the relative asset-class performance in the month just ending. Three rules of thumb.

1. US-equity outperformance produces dollar-selling. When US equities outperform foreign equities, foreign-based equity managers with dollar-hedged portfolios have grown-in dollar hedges that need to be reduced. The rebalance sells dollars into the fix. This is the dominant flow on months when the S&P 500 outperforms the MSCI ex-US by more than 1 percent.
2. US-equity underperformance produces dollar-buying. The reverse: when US equities underperform, the hedge needs to be increased. The rebalance buys dollars into the fix.
3. Large dollar-index moves during the month can override. If DXY moved more than 2 percent during the month, the currency-hedge rebalance dominates the asset-price rebalance. Today's August ended with DXY up roughly 40 pips on the month (from 98.90 opening to 99.28 closing), a modest move; the equity performance dominates.

August 2026 saw the S&P 500 gain roughly 2.1 percent while the MSCI ex-US gained 1.4 percent. That is a 70bp outperformance gap; not extreme but enough to lean the month-end rebalance flow toward dollar-selling. That is what showed up on today's tape as the 22-pip DXY fade in the 3-4 PM London window.

The three interaction patterns with macro flow

The month-end rebalance flow does not exist in isolation. It runs into whatever macro flow was already on the tape. Three interaction patterns.

1. Same-direction reinforcement. If the macro flow and the rebalance flow lean the same way, the aggregate move is larger than either alone. This is the shape when a soft NFP prints on a month-end where equity performance was flat; the dovish flow and the dollar-selling rebalance both push DXY lower and the day's range is unusually large.
2. Opposite-direction cancellation. If the macro flow and the rebalance flow lean opposite ways, the aggregate move is smaller than either alone and the intraday tape is choppy. This is today's shape: the post-Warsh distribution-flip flow leans dollar-bid, the equity-outperformance rebalance leans dollar-offer, and the net tape is a 27-pip range with a 6-pip close.
3. Fix-driven overshoot and retrace. If the macro flow was quiet and the rebalance flow was heavy, the fix produces an overshoot in the direction of the rebalance that retraces in the 30 minutes after the fix. This is the shape that classical FX-flow research (Evans-Lyons, Melvin-Prins) identifies as the pure rebalance signature.

How to identify the rebalance footprint on the tape

Four measurable signatures. Three or more visible during the 3-4 PM London window identify the rebalance flow.

1. Directional flow during 3:00-3:55 PM London. A steady 5-10 pip drift in one direction in the 55 minutes before the fix, without a data catalyst, is presumptive rebalance flow. On today's tape, EUR/USD drifted from 1.1595 to 1.1608 in that window without a catalyst; that is a 13-pip rebalance signature.
2. Volume spike at the fix. The 3:55-4:05 PM London window sees a 3-4x volume spike versus the trailing average for that window. Every month has some spike; a rebalance-heavy month has an especially large one.
3. Partial retrace after the fix. A 20-40 percent retrace in the 4:05-4:30 PM London window is the signature that a rebalance flow was the driver rather than a directional macro flow. On today's tape, EUR/USD retraced 6 pips of the 23-pip pre-fix move; that is a 26 percent retrace, right in the middle of the band.
4. Cross-check against other pairs. If EUR/USD moved on rebalance flow, USD/JPY and GBP/USD should show the same fix-window signature. If the move is only in one pair, it is not a rebalance flow; it is a pair-specific catalyst.

What the framework says about the next few sessions

Two forward implications. First, the month-end rebalance flow is over. Starting Tuesday September 1 the tape is driven by data and macro flow only; the intraday footprint should look different from today's, with less fix-window activity and more data-window activity. Second, the equity performance that drove today's rebalance (US outperformance) is itself a function of the flip on Friday (post-Warsh hawkish is dollar-bid, dollar-bid is US-equity outperformance in unhedged portfolios); the equity performance and the rebalance flow are running on the same fundamental. If Friday's flip extends over the next four weeks, September's month-end will again lean dollar-selling; if the flip fades, September's month-end will lean the opposite.

Related reading

• Today's analysis piece: the Monday tape that motivates this framework.
• A Chair keynote flipping the distribution: Friday's framework that produced the macro flow the rebalance ran into.
• FX intervention: adjacent flow-mechanics piece on official flows that share some of the fix-window signatures.
• Correlations: the framework for reading whether the fix-window move was rebalance flow (multi-pair) or pair-specific catalyst.