Friday's rally made for a reassuring closing bell. The Nasdaq Composite gained 1.1% and the Philadelphia Semiconductor Index advanced 4.2%, with Advanced Micro Devices rising 11%. But the rebound followed a 5.5% Nasdaq plunge on Thursday and did not prevent a 3.4% loss for the week, the fourth consecutive weekly decline. The index remained more than 10% below its recent high, according to Reuters.
Why the Last Session Feels Like the Whole Story
Recency bias is the tendency to place disproportionate weight on the most recently observed outcome. It is particularly tempting when the final observation is dramatic and positive. Friday supplied a clean reversal narrative, but not a clean change in trend. The arithmetic matters: a 5.5% loss requires approximately a 5.82% gain to recover the same starting value. A 1.1% rebound recovers only a fraction of that drawdown.
Another behavioural trap runs in the opposite direction. After four losing weeks, investors can become anchored to the idea that each bounce must fail. Neither reaction follows from the price series alone. The right question is whether earnings expectations, valuations, financing costs or the investor's personal liquidity requirements have changed enough to warrant a different allocation.
Separate a Market Signal From an Emotional Signal
The week's selloff reflected concerns about the cost of building AI infrastructure and the possibility of greater scrutiny following the US midterm elections. Friday's rebound showed that buyers remained willing to own the same theme at lower prices. It did not prove that those concerns were resolved. Reuters reported that the S&P 500 lost 2.7% on the week despite Friday's advance.
For advisors, a useful intervention is to present Thursday, Friday and the full week together, rather than leading with the most recent close. Review whether a client's target weight has actually drifted outside its rebalancing band. If it has not, the urgency to trade may be psychological rather than financial.
Chart uses the November 5 house presentation, with values labelled at each observation. The plotted values and periods are identified in the chart header and source line.
The editorial conclusion is conditional: the next verified release may strengthen or weaken this interpretation. Advisors should keep client-specific suitability, tax circumstances and time horizons central to any decision.