U.S. stock markets will be closed for a second day on Tuesday, as Wall Street turns its attention to whether markets would be able to resume functioning on the month's final trading day on Wednesday.

Wednesday is a key trading day because it marks the end of the month, when traders price portfolios.

The bond markets will also close on Tuesday, with traders aiming to reopen on Wednesday.

Sandy forced the first weather-related shutdown of U.S. stock market in 27 years right in the middle of the earnings season, prompting dozens of companies to delay their quarterly results.

If the NYSE headquarters and trading floor are unavailable on Wednesday, trading in NYSE-listed securities will be executed on the Arca exchange, the exchange operator said in a notice issued to traders late Monday. (r.reuters.com/der63t)

NYSE Arca will offer firms the ability to test the opening and closing auctions on NYSE Arca on Tuesday from 8 a.m. Eastern Time (ET) until 12 noon ET, the exchange said.

Opening auctions will run at 9:30 a.m. ET (1330 GMT) and closing auctions will run at 12 noon (1600 GMT), the exchange said.

"We stress that, as of now, there has been no damage to the NYSE Euronext headquarters that would impair trading floor operations," NYSE said in the notice.

The NYSE's headquarters is a few hundred yards (metres) up the street from areas of lower Manhattan that have been evacuated.

The contingency plan was described as "precautionary" given the unpredictability of the storm that has flooded parts of New York city.

Nasdaq OMX said in a trader alert late on Monday it would operate its production system in a testing capacity from 7:30 a.m. (1130 GMT) to 12 p.m. (1600 GMT). (r.reuters.com/fer63t)

In the event that the markets are able to open on Wednesday but the NYSE headquarters and trading floor in lower Manhattan are unavailable for trading, NYSE Arca would open and trade Tape A equities as usual.

NYSE and the smaller NYSE MKT would remain closed as per the contingency plan.

The NYSE had said on Sunday it planned to close its trading floor and to move all trading to its electronic market.

It backtracked on that idea after traders and regulators expressed concern about moving everything to the all-electronic venue, a plan tested on March 31 but never used live, given the difficulties and low staffing levels due to the storm.

(Additional reporting by John McCrank; Editing by Rodney Joyce)

• A Permanent Economic Emergency