Donald Trump Jr.’s new book hit No. 1 on the New York Times best-seller list this week — “but with a big caveat,” book insiders noted.

The tome, “Triggered: How the Left Thrives on Hate and Wants To Silence Us,” shot to the top of the Times’ nonfiction list. But a source noted of Trump’s achievement: “It has the big dagger [symbol] next to it, which means a large portion of the sales came from bulk orders.”

The source added: “It’s known in the industry as the ‘deadly dagger.’ A rare penalty that is only called for flagrant fouls,” such as when an author or someone close buys large quantities.

It’s at Times editors’ discretion when to plunge the dagger. Fine print below the best-seller list explains, “Sales are defined as completed transactions by vendors and individual end-users during the period on or after the official publication date of a title. Institutional, special interest, group or bulk purchases, if and when they are included, are at the discretion of The New York Times Best-Seller List Desk editors based on standards for inclusion that encompass proprietary vetting and audit protocols, corroborative reporting and other statistical determinations. When included, such bulk purchases appear with a dagger (†).”

Don Jr.’s book came out Nov. 5. Reports said sales have been boosted by the Republican National Committee, which is sending out copies as a fund-raising incentive. But an RNC rep told the Times: “Using books as a means to fund-raise is standard practice from political parties on both sides of the aisle … ‘Triggered’ has been very popular among our supporters, helping us raise funds to support the re-election effort.”

Hachette imprint Center Street told us: “We are thrilled that ‘Triggered’ is No. 1 … Mr. Trump had an amazing book tour with nearly 20 book signings in nine states. Most of the locations sold out of the books, with thousands of books sold during the events. The demand was overwhelming. Regarding the RNC, they didn’t purchase books from Hachette, and we don’t have knowledge of third-party book purchases.”