The move by Nasdaq to sign on NYSE companies heightens competition between the Big Board and the electronic exchanges.

It couldn't come at a worse time for the NYSE - and the Nasdaq is trying to get others to dual-list as well.

The NYSE is still trying to regain the confidence of the financial community after the wrenching Grasso scandal, in which the former NYSE chief was paid $190 million by board members he regulated.

Large investors and major mutual fund companies have slammed the exchange, and now the NYSE's new leadership must develop a strategy to combat wider competition than it's ever faced.

"You are seeing a form of rebellion by some companies," said Jerry Putnam, CEO of Archipelago, a rival exchange to both Nasdaq and the NYSE. "They are expressing their displeasure about what is happening at the NYSE."

The companies include Hewlett-Packard, Charles Schwab, Apache Corp., Cadence Design Systems, Countrywide Financial and Walgreen.

Listing on more than one exchange is not expected to change the price or trading of the stock significantly.

But the move symbolizes the end of the Big Board's listings dominance.

"The issue for the companies was market structure and what our market structure will mean to investors," Nasdaq CEO Robert Greifeld told The Post. "That means speed and certainty of execution, deeper liquidity and a more thorough price discovery mechanism," he said.

The six NYSE-listed companies said the move to list on the all-electronic Nasdaq was intended to create more activity in the stock and more transparency - a dig at the NYSE's floor-based trading system.

The NYSE delivers the best price more than 90 percent of the time, but without the transparency and speed some institutional investors want.

"It was a no-cost look at something that could increase competition among the markets," said Walgreen spokesman Michael Polzin. Nasdaq will waive listing fees for the first year, a perk that Polzin said "made our decision easier."

The competition shouldn't cut too much into the NYSE's market share unless the Securities and Exchange Commission changes a controversial rule that guarantees the exchange with the best price for a stock gets to execute the transaction.

The NYSE would like to see this "trade-through" rule remain intact, but most of its competitors want it eliminated.

"Our own market share will grow over time, and reform of trade-through will be an acclerant to that," Greifeld said.

"Obviously this is a major competitive effort being launched by Nasdaq," said Columbia Law School securities expert John Coffee. "Behind it is the desire of Fidelity and large institutional investors to get a venue on which they can obtain better liquidity and faster execution."