The New York Stock Exchange just had a trading snafu.

NYSE suffered an outage on its Arca marketplace that meant it couldn’t carry out a closing auction for a number of exchange-traded funds on Monday.

“The matching engine crapped out in the last few minutes, and the closing auction didn’t get done,” one market participant told Business Insider.

The result is that trades on NYSE Arca, NYSE’s ETF trading venue, went unexecuted.

Here’s how it went down:

    4:11 p.m. - NYSE said in a notice: "NYSE Arca Equities is currently unavailable in all Tape A, B and C symbols. All live orders will be cancelled. Additional information will follow as soon as possible." 4:37 p.m. - NYSE set out how the closing prices for those symbols that did not complete an auction would be determined. Under the current rules, the closing price in this kind of an event is the volume weighted average price of all last sale eligible trades for the last five minutes of the day. 4:46 p.m. - NYSE said some closing price indications were being reviewed. 6:51 p.m. - NYSE published a list of NYSE Arca Official Closing Prices for all NYSE Arca listed symbols with last sale eligible trades , including those with Corrected Official Closing Prices.

Then, at 8:59 p.m., NYSE put out a statement saying that the underlying cause of the disruption had been identified and remediated, and that exchange-traded product holders that wanted to file a claim for compensation should do so by 9.30 a.m. on March 21.

Here's the full statement:

On March 20, 2017, the NYSE Arca Equities trading platform experienced a system issue resulting in a subset of symbols failing to conduct a closing auction or transition from the regular trading session to the late trading session at 4:00 p.m. The Exchange suspended trading in all symbols at approximately 4:13 p.m. and cancelled all open orders. In securities that failed to transition from the regular trading session to the late trading session, orders designated for the regular trading session may have executed after 4:00 p.m. The Exchange invoked its procedures for determining the Official Closing Price ("OCP") when the Exchange is unable to conduct a closing transaction in one or more listed securities due to a systems or technical issue. OCPs for NYSE Arca-listed securities were subsequently transmitted to the SIP, which can be found here.

The underlying cause of the disruption has been identified and remediated.

ETP Holders seeking to file a claim under NYSE Arca Equities Rule 13.2 are reminded that any claims for compensation in relation to an exchange system failure must be submitted to [email protected] by 9:30 a.m. on March 21, 2017 in order to be eligible for consideration.