eBay and auction house Sotheby’s have cemented a deal to stream auction sales worldwide. eBay could begin streaming New York public auctions as early as fall, with the potential to later add exclusive online-only sales and broadcast's from additional Sotheby’s hubs including Hong Kong, London and Paris. The benefits for both companies are clear: Sotheby's would gain access to eBay's 145-million-strong customer base, while eBay could trade on Sotheby's air of authenticity, lending credibility to high-end, expensive purchases made through the site. Shares of Sotheby's are higher on the news, while eBay has slipped slightly. TheStreet's Keris Lahiff reports from New York.