Quote from eSignal Support:
eSignal provides an institutional quality feed that fully supports CID's (corrections, insertions and deletions). If a bad tick is sent by the exchange and then corrected, it's automatically adjusted in our charting. Very few vendors can claim that.
We'd need some specifics to directly address your question but I do see a low spike on QQQQ at 14:30 ET. There was a trade at 29.5967 with a size of 12,000. The sequence # is 1981078 and I confirmed that trade with another institutional data vendor. I have not seen a cancellation or correction to that tick as of yet so it is still considered valid. You can use our bar editor to manually adjust for your charting needs.
For future reference, please use the Data Inquiry forum on eSignal Central to post any data related concerns.
Thanks.