With less than 1 you're not a shareholder, only your broker is. All you have is a contract with your broker about how they split a part of the profits of their share in Berkshire Hathaway.
Not really. A small shareholding is still a shareholding. You can still go. If you read the meeting instructions they ask for a statement showing you have a holding in street name. I've been a couple of times flying from London to Omaha. It was kind of fun.
Also you are technically and legally a shareholder even if your broker holds the shares on your behalf as is usually the case these days, and attending any shareholders meeting is a legal right whatever the size of the shareholding.
Although just now they are online due to covid but I'm sure the physical meetings will return.
If you do hold 0.001 shares with a broker and you want to go you should request with them to be sent the annual report, also a legal right, and that'll have the invite card. Or if not you can phone Berkshire and ask for one.
A small shareholding counts, but that still means owning at least 1 share. Anything less means you don't own the share. Fractional shares are a different construction (compared to the normal case where the broker holds your real non-fractional shares for you) between you and some brokers that offer it, which result in you not really owning the share and thus not going to the shareholder meeting.
