Month-End And Quarter-End Flows

A lot of trading volume near the end of a month or quarter has nothing to do with new information about a company — it's mechanical, driven by calendar deadlines that many institutions share simultaneously. Index funds must rebalance to match their benchmark's official reconstitution dates, which cluster at quarter-end; pension funds and balanced mandates often rebalance back to target stock/bond weights on the same schedule; and many funds report performance monthly, creating an incentive to trade into positions that will look good ("window dressing") right before the reporting snapshot.

Because so many large players face the same deadline at once, month-end and quarter-end flows can be large enough to move prices temporarily even without any change in fundamentals — a stock being added to an index sees concentrated buying right around the effective date, and broad "risk-on" or "risk-off" rebalancing flows can push whole asset classes in the same direction for a few sessions purely from calendar-driven mechanics.

Because the effect is driven by structural, recurring deadlines rather than by information, it tends to partially reverse once the deadline passes — which is exactly the signature that separates a calendar-flow effect from a genuine, information-driven price move.