You probably have to be with a full service broker. If you don't have millions and you are offered shares then it's probably a good move to refuse them. It means the big boys aren't interested.
Arm's IPO preparations are being led by Goldman Sachs Group Inc (GS.N), JPMorgan Chase & Co (JPM.N), Barclays (BARC.L) and Mizuho Financial Group (8411.T). I wouldn't hold much hope there will be any trickle-down, but you'll know when the offerings docs post. Would not expect to see the full selling group until the filing.