Regional Exchanges Rush to Match NYSE Hours : Securities: The smaller markets are submitting plans to the SEC to expand their trading day too.

NEW YORK —  Defending against the New York Stock Exchange’s move into after-hours trading, the nation’s regional exchanges are proposing competing systems for swapping stocks after regular market hours.

The NYSE’s plan to trade individual stocks and baskets of securities in two sessions after the traditional 4 p.m. close generated unanimous criticism from the smaller regional exchanges and the over-the-counter market.

But approval of the NYSE plan by the Securities and Exchange Commission on Monday has forced the opponents to propose comparable systems for after-hours trading.

“We’re going to have the same concerns, but the SEC has reviewed it and they put their blessing on it and we’re going to have to move ahead on that basis,” Paul Adair, a vice president at the Philadelphia Stock Exchange, said Tuesday.

The Philadelphia, Pacific, Boston and Midwest stock exchanges are readying proposals aimed at staunching a projected loss of business to the NYSE in the after-hours sessions. Any changes in their trading routines require SEC approval.

The NYSE plans to begin trading June 13 in two overlapping “crossing sessions” that will extend the trading day until 5:15 p.m. The sessions are intended to recapture market share that has shifted to regional and overseas markets.

The move by the nation’s biggest stock exchange is the first step toward round-the-clock securities trading by the year 2000.

The first after-hours session would last from 4:15 to 5 p.m. Orders to buy or sell individual stocks would be matched up and executed by computer. Prices would be restricted to their 4 p.m. close on the NYSE.

The second session, from 4 p.m. to 5:15 p.m., will accommodate trades of baskets containing at least 15 individual stocks with a total value of more than $1 million. It is intended to attract computerized program trades by big institutional investors now being done in London.

The main complaints involve the first session, particularly guidelines on how “limit orders” are handled. Limit orders are instructions from customers to buy or sell stock at a particular price. The NYSE will carry such orders into the after-hours session.

That means limit orders that are placed but unfilled on a regional exchange would get a second crack on the NYSE--drawing away business.

The Pacific, Philadelphia, Boston and Midwest stock exchanges have asked or plan to ask the SEC to approve measures that would keep such trades from leaving their exchanges.

“The thinking here is we may potentially lose some crosses to New York,” Pacific Stock Exchange spokesman Dale Carlson said. “We’re going to try to hang on to some of that.”

The Pacific exchange, located in San Francisco, wants to offer a crossing session for individual stocks, like the NYSE’s, to protect its orders. But it does not plan to propose a basket trading session.

The Midwest exchange, located in Chicago, and the Boston exchange are asking the SEC only to allow specialists, who regulate trading flow, to execute their own limit order trades for customers at 5 p.m. New York time.

Those two exchanges will not accept new orders in the session to buy or sell shares at the NYSE closing price, saying they didn’t anticipate enough business to make it worthwhile.

The Philadelphia exchange, however, has asked federal regulators to approve a clone of the NYSE plan, calling their action “solely a competitive response.”