According to information we received from the APA Style Blog, "Stock quotes are essentially searches, and searches cannot be references, as they are not retrievable. Instead, a search is part of your method."
In the appropriate place in the text of your paper, describe the search that you used to get the stock quote, including the name and URL of the website you searched, the company name and ticker symbol, the date searched, and the price. You do not need to make an in-text or reference list entry for this information.
You may need to cite a stock price at a specific point during the day, or the closing price at the end of the day. Examples of both are given below.
Examples
Closing Price: "On December 13, 2021, Yahoo! Finance (https://finance.yahoo.com) listed the closing share price for Microsoft Corporation (MSFT) stock as $339.40."
Price as of Day/Time: "As of 3:52 pm EST on December 14, 2021, Yahoo! Finance (https://finance.yahoo.com) listed the price of Microsoft Corporation (MSFT) stock as $328.33."