(Reuters) - Several exchange operators on Tuesday re-enabled routing to Members Exchange (MEMX) after disabling it for a brief period.

MEMX Equities delayed the opening of its pre-market session to 08:45 a.m. ET as the stock exchange encountered an issue. It did not clarify what the issue was.

The exchange normally starts its pre-market trading session at 7:00 a.m. ET, according to its website.

The New York Stock Exchange (NYSE), Cboe Global Markets and Nasdaq were among the exchange operators that disabled routing to Members Exchange during pre-market trading before resuming it after a brief pause.

The issue also led to self-help declarations from the NYSE and Cboe against Members Exchange. Both were revoked later.

A "self-help" is a notification issued by a trading exchange when another exchange is dealing with internal problems in processing trades and orders are routed through alternate venues.

Nasdaq, NYSE and CBOE did not immediately respond to Reuters requests for comment.