Pioneer Natural Resources Co. remains in “no comment” mode on whether it is in discussions with Exxon Mobil Corp. on a potential blockbuster merger, CEO Scott Sheffield said.

Sheffield was asked during this morning’s earnings call about why it did comment on a rumor that it was looking at buying Range Resources Corp. but hasn’t commented on the ExxonMobil rumor.

“We saw our stock get down to $180 [on the Range news],” Sheffield replied. “That’s the only reason we went away from ‘no comment.’”

Range is an Appalachia gas producer, while Pioneer is fully focused on Permian Basin oil. Its stock fell from $233 to $180 upon Bloomberg News’ report of the Range rumor in February.

The Wall Street Journal reported in early April that ExxonMobil is talking to Pioneer about a deal.

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Doug Leggate, an analyst with Bank of America, said in the earnings call, “Your pattern has been not to comment on market speculation, but you did with Range. You broke the precedent.

“The language in that press release was very specific. It said, ‘We are not contemplating a significant business combination.’ Should we assume from that then that it would preclude any discussion with Exxon Mobil?”

Sheffield said that the Range comment was an exception. “You're going to see us always use that ‘no comment’ like every other company does in every other industry.”

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As for any other speculation, “and as I said before, the board will always do what's in the best interest for shareholders,” he concluded.

Leggate asked, then, if Pioneer is or isn’t in merger discussions with a “larger company.”

Sheffield said, “I’ve already answered that question, Doug.”