The company hopes to tap millions of new customers who may prefer mouse- clicking over paddle-waving when bidding for art, jewellery and collectibles.
Also yesterday, At Home Corp, a California company that specialises in delivering high-speed Internet connections to private homes in the United States, revealed that is to buy Excite Inc, the owner of one of the most popular portals on the World Wide Web, for a stunning $6.7 billion in stock.
If completed, the At Home transaction will be largest single deal in the history of the Internet, eclipsing the America Online's recent purchase of Netscape Communications three months ago.
At Home will be paying nearly double Excite's market value, put at about $3.4bn at the close of trading last Friday.
Both announcements offered fresh illustration of the ongoing explosion of consumer and investor interest in all things do to with the Internet.
Recent weeks have been marked by soaring prices among stocks offered by fledgling Internet enterprises, most of which have yet to make a dollar in profit.
One company that has been turning profits is eBay, which has led the way in taking auctions into cyberspace and has become one of the most popular destinations on the Web where consumers enter bids from their PC's for articles for sale.
Among the measures of eBay's success has been its market valuation. Listed publicly only last September, it now has a market value six times that of Sotheby's.
"With the launch of sothebys.com, Sotheby's enters an exciting new era", said Diana Brooks, president of Sotheby's, in New York yesterday.
She made a nod to the success of eBay, while not mentioning it by name.
"It is clear that the Internet is superbly suited for holding auctions," she remarked. The pressure will now be on Christie's, the longtime rival of Sotheby's, similarly to take the cyber plunge.
An important beneficiary of the At Home deal, meanwhile, will be AT&T.
The giant telephone company, which is anxious to harness the Internet, is in the process of acquiring Tele-Communications Inc, which itself has a large share in At Home.
Though it trails Yahoo! among the pioneers of portal sites, Excite should none the less prove powerful in attracting new Internet customers.