AGM=Shareholders Meeting?

AGM = Annual General Meeting and EGM = Extraordinary General Meeting are meetings of the members ( shareholders ) of a limited company. So, AGM is a meeting of members for transacting ordinary businesses of a company.
For how many members present are necessary for a valid meeting, quorum of a meeting, you have to check to the Memorandum and Articles of Association of that company. It is quite a common practice that 2 members present will form a quorum. Any meeting with quorum below the minium number of memebrs present as stated in the Articles is invalid.
After the meeting, the minutes of that meeting must be signed by the Chairman together and also signed by each of the members present in the meeting.

AGM = Annnual General Meeting.
是 one of the "Shareholders Meetings", AGM 不全是 = Shareholders Meeting.

私人有公司的 AGM 要有幾多%的股東出席/簽署會議記錄為有效, 通常要超過50%.,