Why the articles are not enough
The articles of association are the company’s registered, public constitution, and most Thai companies adopt a standard template that says nothing about quorum needs, share-transfer restrictions or reserved matters. The shareholder agreement is the private contract between the people, and it is where the commercial bargain actually lives.
Control: who decides what
Board seats, authorised signatories and a list of reserved matters requiring unanimous or special approval — borrowing, capital expenditure above a threshold, hiring senior staff, new lines of business. Without a reserved-matter list, day-to-day control tends to follow whoever is on the ground, which is rarely what the passive investor understood.
Money: funding, dilution and profits
What happens when the company needs more capital and one shareholder cannot or will not provide it? Funding calls, dilution mechanics and shareholder loans should be written down before the first cash crunch, because that is the moment when an unwritten understanding turns into a dispute about fairness.
Deadlock: the clause nobody expects to use
An even split means neither side can pass a resolution alone, so the first serious disagreement freezes the company unless a mechanism was written in advance — a casting vote, an expert determination, or a buy-sell trigger. Fifty-fifty without a deadlock clause is the most common way a good partnership becomes an unsellable stalemate.
Exit: agreed now, not later
Transfer restrictions, pre-emption rights, drag and tag rights and an agreed valuation method turn an exit into a procedure rather than a negotiation with someone who no longer wishes you well. The same clauses cover the exits nobody plans — death, incapacity, or a shareholder who simply stops participating.