AFAIK controlling shareholder means that the shareholder has more than 50% of the voting power. They or the group they belong to have unilateral control of the company barring some restrictions.
But controlling looks to more about how much voting power and influence you have rather than how many shares, because remember companies can have different classes of shares.
Though looking at this a large but not 50%+ stake can also be "controlling": https://www.upcounsel.com/controlling-shareholder
But controlling looks to more about how much voting power and influence you have rather than how many shares, because remember companies can have different classes of shares.