IG Group Holdings plc was among the best-performing stocks on London’s main board on Thursday, rallying after a harrowing session last week.

The online trading and investments platform had cautioned that profits would come in below expectations because revenue retention was weaker than anticipated, sending the shares sharply lower in a single day. The recovery followed one of the sharpest moves among UK financial stocks in recent weeks.

The rebound does not erase the damage, but it suggests some buyers believe the reaction went too far. Revenue retention measures how much of the trading revenue generated by active clients the company keeps after costs and client movements. When it slips, the business earns less from the same level of customer activity, which was the central concern in the update.

Volatile markets can produce bursts of trading activity that look strong on the surface, yet the underlying profitability depends on how clients behave and how risk is managed.

The warning dragged other platforms lower. CMC Markets p slid at one point, and Plus500 Ltd also dropped before pulling back from its worst levels, with the latter stating that its own trading was in line with expectations for the full year.

Insiders at CMC Markets, including its founder, bought shares in the aftermath, a gesture that tends to attract attention even if it does not settle the debate.

Longer term, the key question is whether the retention issue reflects a temporary shift in client behaviour or a deeper change in how customers trade.

Investors will be searching for detail on the cause of the retention shortfall, whether it is cyclical or structural, and how management plans to respond. Updates on client numbers, cost control and the share buyback programme are also on the radar.

Online trading platforms have enjoyed a period of strong client activity, but they are exposed to changes in market volatility, regulation and competition from cheaper rivals. Profit warnings from one company often trigger a broader reassessment across the sector.