To make placeholders visible, go to Edit > Preferences > Investment Transactions and make sure the Show hidden transactions box is checked.
Placeholders will have a gray background in the account’s transaction list (register) even if they are not selected, and will have “Entry” in the Action column.
Placeholders compensate for missing or incorrect investing transactions by forcing Quicken’s share balance for a security to match a specified value.
Placeholders also prevent new transactions like Bought and Sold prior to the Placeholder date from affecting the account’s cash balance. This shows up as N/A in the Cash Amt column of the transaction list.