The conversation between human and AI assistant.
[|Human|] Find a stock's closing price on a given day.
[|AI|] As an AI language model, I don't have the ability to access up-to-date financial information, unfortunately. To find the closing price of Apple stock on June 15, 2021, you can visit a financial news website or search for historical stock data on a platform that provides financial information.
[|Human|] 
Find a stock's closing price on a given day.