buy a stake in, invest in (a business)
“入股，”约翰娜说。
“Buy in,” Johanna said.
不行，就当你入股吧
No, just consider it your investment in the business.
— 叶问 (2008)
“入股？”
“Buy a stake?”
其他人都在入股，你也该入一份。
Everyone else is buying in—you should get a stake too.