UPDATE 1-CA moving to Nasdaq, keeping trading symbol

(Adds detail, background, quote)

NEW YORK, April 16 (Reuters) - Business software maker CA Inc CA.N said on Wednesday it would move its stock exchange listing from the New York Stock Exchange to Nasdaq, where its shares will trade under the "CA" symbol effective April 28.

Islandia, New York-based CA will become the first company to list on Nasdaq with a two-letter stock symbol.

"We believe that like cell phone (numbers), trade symbols should be portable," said Bruce Aust, an executive vice president at Nasdaq. "People get attached to their symbols."

Nasdaq (NDAQ.O) says portability is an important selling point as it tries to woo companies away from the NYSE (NYX.N) or the American Stock Exchange, because a ticker symbol can be an important part of a company's brand.

Since February 2007, Nasdaq has been able to trade in one- two- three- and four-letter symbols, following U.S. Securities and Exchange Commission approval, although new companies listing on Nasdaq still have to use four- or five-letter symbols.

In December, DirecTV (DTV.O) switched over to the Nasdaq from the NYSE, becoming the first company with a three-letter ticker to make the move.

Since 2005, when company moves between the two competing exchanges accelerated, 7 companies have moved to Nasdaq from the NYSE (25 have moved from the Amex), while 24 have moved from the Nasdaq to the NYSE. But Nasdaq claims higher market capitalization of its new members at the time of their move to Nasdaq.

CA spokeswoman Jennifer Hallahan explained the exchange switch to Nasdaq saying "it is to be more closely aligned with our peers and other software companies." (Reporting by Paul Thomasch and Phil Wahba in New York, and Jim Finkle in Boston; Editing by Tim Dobbyn)