In a move likely to be viewed as protecting its PayPal Inc., eBay Inc. has barred sellers from using Google Inc.'s new payment service.
The San Jose online auction giant also announced Thursday that Jeff Jordan, PayPal's president since December 2004, would leave in the fall "to spend more time with his family." Rajiv Dutta, who has been with eBay since 1998 and is currently the president of its Internet phone unit, Skype, will succeed Mr. Jordan.
Google, which dominates the online search industry and has become a growing force in several other Internet business lines, entered the payment market last week by introducing its long-awaited Checkout service.
After that announcement at least two analysts reduced their earnings estimates for eBay.
Catherine England, an eBay spokeswoman, said it updated its Safe Payments Policy on Wednesday, adding services from several companies, including Google, to the list of "payment services not permitted on eBay."
The decision to update the policy was unrelated to any concerns that one of the biggest online forces had entered PayPal's market, she said. "We are evaluating the service, not the company behind it."
She said eBay supports only companies with a demonstrated track record, and Checkout is "relatively new."
Though the policy says that Checkout cannot be used, in practice this means that eBay sellers cannot advertise that they accept it; Ms. England said that if both a buyer and seller wanted to use Checkout for a purchase, the transaction would go through, and eBay likely would never notice.
Google said in an e-mail, "Billing and payments have historically been a core part of Google's advertising programs and online services," and Checkout was thoroughly tested with merchants.
Wall Street sees Checkout as a major threat to eBay's revenue.
"We have concluded the Checkout is a greater challenge to PayPal's long-term growth than is widely recognized," Mark Mahaney, an analyst with Citigroup Global Markets, wrote in a research note published Wednesday.
Though PayPal offers many advantages over Checkout, he wrote, Google's transaction speeds are faster than its more-established rival's, and its fees are more attractive to merchants.
In the space of a year "Google has developed an integrated merchant checkout process that, for consumers, is materially easier and quicker to use than PayPal," Mr. Mahaney wrote. "This speaks volumes about Google product development skills and PayPal's lack of innovation."
He reduced his 12-month price target for eBay's stock to $40, from $51. Paul Keung, an analyst with Canadian Imperial Bank of Commerce's CIBC World Markets, cut his 12- to 18-month target for eBay shares by $10, to $35.
On Thursday the shares fell 5.32%, to close at $26.85.
Merchants using checkout pay processing fees to Google but are eligible for rebates if they also advertise with Google.
It charges a base fee of 20 cents, plus 2% of the transaction; PayPal charges a base of 30 cents, plus at least 2.2% for purchases of up to $100,000.
Dan Schatt, a senior analyst for the market research firm Celent LLC, said he was not surprised eBay's has blocked Checkout.
Google is "a direct threat to eBay," he said. "It's potentially cheaper for a merchant to place their ads with Google than to list on eBay."
Google does not need eBay for Checkout to thrive, Mr. Schatt said, because it can link Checkout to both ads on its search engine and its Google Base service.
