Dallas-based Heritage Auctions say 2012 was their best year to date, with total sales of more than $860m.
While American coins remain the core of Heritage's business with $218.68m in sales in 2012, Steve Ivy, co-chairman and chief executive, says the firm is "attracting new buyers across more categories than ever before. Diversification has been key to our success".
World and ancient coin sales have seen marked growth over the last four years, increasing 40% to $25.4m last year, while a 20% year-on-year increase in picture sales saw this category bring $45.5m.
From January to December 2012, Heritage sold antiques and decorative arts totaling $7.27m (an increase of 32%), $7.3m in film posters, $19.24m in sporting memorabilia, $7.27m in rare books and manuscripts and comic book and comic art exceeding $37m.