March 23 (Bloomberg) -- The New York Stock Exchange plans to comply next week with rules designed to offer investors a guarantee that they are getting the best price on their trades, according to a notice sent to members.

The NYSE said in the notice that it plans to route orders to the International Securities Exchange and the NASD's Alternative Display Facility whenever those markets have better prices for stocks. The exchange tested the routing this week.

``The rollout is expected to conclude the week ending March 30, pending continued successful implementation of the new software,'' the NYSE said in the notice today.

Regulation National Market System, or Reg NMS, took effect March 5. It requires exchanges route orders to the market with the best price available for automatic execution. While the NYSE complied with most provisions by completing one of the biggest overhauls its trading system in three decades, it was unable to connect to all rival markets.

The International Securities Exchange and the NASD Alternative Display Facility aren't part of the Intermarket Trading System, a computer network that links the NYSE with other securities markets.

Knight Capital Group Inc.'s Direct Edge relies on the NASD system to complete transactions. The International Securities Exchange, which is based in New York, has grown to handle about 6.5 million shares a day after six months of trading.

To contact the reporter on this story: Edgar Ortega in New York at ebarrales@bloomberg.net.

Last Updated: March 23, 2007 19:04 EDT