By Paula Laier
SAO PAULO, April 18 (Reuters) - Shares of Brazilian card payment processors Cielo SA , PagSeguro Digital Ltd and StoneCo Ltd fell sharply on Thursday after rival Itaú Unibanco Holding SA's card-processing unit cut interest rates for small- and medium-sized merchants.
StoneCo and PagSeguro, which are both listed in New York, were down 22.5 percent and 11.5 percent, respectively, while Cielo fell 8 percent on the São Paulo stock exchange.
The bank's two requirements for the service are that clients have a checking account with Itaú and annual revenues no higher than 30 million reais ($7.63 million), Itaú said in a statement.
Card processors in Brazil charge discount rates to advance cash in a business that has become increasingly important to their business models.
Analysts at Credit Suisse said in a note to clients that this payment model was likely to become "the new standard," hurting all card processors' results.
"All in all, as a reference, we estimate an annualized net profit impact of 32 percent for Stone and 19 percent for Cielo, all else held equal," Credit Suisse analysts wrote.
The impact on PagSeguro, however, may be less painful, as it already offers payments for micro-merchants in two days.
Brazil's antitrust watchdog, Cade, sent Itau a request for more information on the decision to cut interest rates, asking for an answer by May 3, according to a document released on Thursday.
($1 = 3.9332 reais)
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