Exchange says Nasdaq/Finra TRF -- a service dark pools and other off-exchange venues use to report stock trades -- is experiencing technical issue.

“Nasdaq is working on failing over affected connections and customers may see further disconnections as this process takes place,” Nasdaq says in notice at 9:32am.

NOTE: Systems like Nasdaq TRF knit together U.S. stock trading, which is spread across dozens of markets. Though trades could happen even without the TRF, they might not get recorded publicly.