Warren Buffett’s “Mystery Stock”?

Note on Warren Buffett’s “Mystery Stock” (13F confidential treatment in 2023 Q3 and Q4):

Berkshire would be required to report its holding if it exceeds a 5% stake in a company. If, for example, that company is JPMorgan Chase ($JPM) (my guess) with a capitalization of $520 billion, 5% equals $26 billion.  An investment of this size would “move the needle” and qualify as an “elephant” that Warren Buffett has been seeking. Berkshire held $157 billion in cash and cash equivalents on September 30, 2023.