Headaches for traders with NYSE glitch near market close

[NEW YORK] NYSE Group sowed confusion among traders after a technical error hobbled one of its exchanges on Monday.

NYSE Arca, the largest US listing venue for exchange-traded funds, shifted to backup methods for calculating the closing prices for most securities, according to a series of trader alerts. The exchange closed early for its after-hours session, saying it wouldn't resume trading until 4 am New York time on Tuesday. Kristen Kaus, a spokeswoman for NYSE, declined to comment beyond the trader alerts.

While high-profile exchange malfunctions are becoming rarer in the US$27 trillion US stock market, Monday's fault highlights the importance of closing auctions, which have assumed a bigger role with the growth of passive investing. Out of 1,230 Arca-listed securities, only 53 were closed through the normal auction-drive method. Those that weren't include the US$237 billion SPDR S&P 500 ETF and US$33 billion SPDR Gold Shares ETF, two of the largest exchange-traded funds in the world.

"One could argue the role of NYSE official closing prices is one of the most important in the market," Spencer Mindlin, an analyst at Aite Group LLC, said by email. "Millions of portfolios and retirement accounts depend on the closing prices of NYSE-listed stocks and ETFs." Not knowing the closing price for a security can be a source of risk for traders, leaving fund managers unable to accurately tally the value of their holdings.

The error comes as NYSE still faces fallout from a separate technical error almost two years ago. Parent Intercontinental Exchange Inc revealed last month that Securities and Exchange Commission investigators believed a 3 1/2-hour New York Stock Exchange outage on July 8, 2015, violated the law.

NYSE first reported it was investigating a technical issue at 4.07 pm on Monday, just minutes after the regular trading session ended. The bourse said in a later message to customers that ETF holders who wanted to be compensated for issues relating to the malfunction should submit their claims by 9.30 am Eastern time on Tuesday. The company also said the underlying cause of the disruption had been identified and fixed.

NYSE Arca saw severe disruption to its market open in Aug 2015. While that wasn't caused by faulty technology, a later analysis by the US Securities and Exchange Commission found that rules at the venue contributed to more than 1,000 trading halts in 327 exchange-traded products. In December, trading at the exchange was halted for 15 minutes because of a technical issue, though traders said the impact was minimal as orders flowed to other markets.

Mindlin said that glitches can have a competitive impact in a sector where Nasdaq Inc. and CBOE Holdings Inc. are battling for business. CBOE's Bats unit hired ETF executive Laura Morrison from NYSE, and in March 2016 bought ETF.com, a data and news provider for the industry.

"These consequences of outages like this highlight the importance of stable and trustworthy technology at the market venue where an ETF issuer chooses to list its products," said Mr Mindlin. "The marketplace for ETF listings is very competitive. Bats and Nasdaq have been attracting listings as fund providers look to diversify."

BLOOMBERG