US Influence15 May 2026 11:28
Hi LB, AIM is completely frozen from 16:30 to 08:00, so nothing that happens in the UK can move the valuation overnight.
But the US line (AVCTF) continues trading until 21:00 UK time, and market makers use that US session to set the indicative opening price and market cap for 08:00.
So any change in market cap between the UK close and the UK open is effectively the ‘US sentiment adjustment’.
It’s not that the US trades on AIM — it’s that AIM reprices because of the US session.
On the market cap vs share price point: they’re mathematically linked, but institutions screen on valuation bands, not the last traded price.
Crossing thresholds like £500m, £750m, £1bn changes which funds can invest, so market cap is the cleaner indicator of how the company is being classified.
US investors can buy AIM shares, but most US brokers don’t offer AIM access, so they use AVCTF instead. That’s why the US line matters.