But several executives cautioned not to read too much into a single week of ratings.

The executives cautioned that the negotiations could still break down.

But other executives cautioned that the fine points of an agreement would take several more days to work out.

But the banks' top executives also cautioned that a strong credit environment, like all good things, would eventually come to an end.

An executive with knowledge of the negotiations cautioned that the deal could still founder.

Some executives cautioned Sunday night that the deal was still not signed, and might fall apart.

Any deal is far from guaranteed, one executive cautioned, and not expected to be announced before next week, if at all.

The executives also cautioned that the two companies could still abandon the effort.

But some executives are cautioning that increasing production will take time.

The executives also cautioned that it was still possible the deal could fall apart.