dissenting:
Because I believe that extraneous evidence was admissible and that there are genuine issues of fact to be resolved whether the parties entered an enforceable contract, and concerning Bretz’ estoppel claim, I respectfully dissent.
I. STATUTE OF FRAUDS
There is no dispute that under Montana law a contract for the sale of securities, as here involved, comes under the statute of frauds, Mont.Code Ann. § 30-8-319 (1987). The question at issue is not whether evidence other than the contents of the writings is admissible to prove the terms of an agreement, see Mont.Code Ann. § 28-2-905 (1987), but whether the parties made a valid agreement. “When the validity of the agreement is the fact in dispute” extrinsic evidence is not barred by the parol evidence rule. MontCode Ann. § 28-2-905(l)(b) (1987).
The terms of the agreement were set forth in the correspondence. On August 23,1983, PGE responded to Bretz’ offer for the securities, stating:
Consequently we would be receptive to an offer of $2,750,000 from you and your associates provided the matter could be closed in a timely manner as proposed in your letter of August 10, 1983.
I would appreciate you resubmitting your offer on the above basis.
Bretz responded on August 29,1983 with an “Acceptance of Offer” stating:
Foregoing Offer is amended to state a purchase price of $2,750,000.00. The joint venture accepts your counter-offer which includes our terms as set forth in *416letter, as above. We consider that a contract for sale exists.
At that point there was no dispute as to the terms of the agreement. The only issue is whether there was a valid agreement. All that is necessary to satisfy the Montana Statute of Frauds is that the writing signed by the defendant is “sufficient to indicate that a contract has been made for sale of a stated quantity of described securities at a ... stated price_” Mont. Code Ann. § 30-8-317(1) (1987). Extrinsic evidence is admissible under an exception to the parol evidence rule not only when the validity of the agreement is the fact in dispute, but also when the documents relied on to satisfy the Statute of Frauds are ambiguous. Mont.Code Ann. § 28-2-905(2) (1987); Empire Steel Mfg. Co. v. Carlson, 622 P.2d 1016, 1021 (Mont.1981).1
PGE stated it would be “receptive to an offer of $2,750,000.” Receptive is defined as “1. Capable of or qualified for receiving. 2. Ready or willing to receive favorably: receptive to their proposals." The American Heritage Dictionary of the English Language 1088 (1970) (emphasis in original). Contrary to the majority’s assertion that only one reasonable conclusion could be drawn from the August 23 letter, it could reasonably be read as an offer “to receive favorably”, i.e. to accept, Bretz’ indication of agreement to the terms of the August 23 letter. Under this interpretation, PGE had no discretion to refuse Bretz’ acceptance, and thus Bretz had the power to close the deal unilaterally.
Another factor indicating that the August 23, 1983 letter was a counteroffer is that, in contrast to the PGE letter of August 5, 1983, it did not indicate that the $2,750,000 price was subject to approval by PGE’s board.2
An examination of the August 23 letter and the other correspondence leads to the conclusion that it could reasonably be read as a binding offer. Nevertheless, because the final sentence of the letter states, “I would appreciate you resubmitting your offer on the above basis,” I believe the letter is ambiguous whether it constituted a counteroffer or an invitation to submit an offer. Accordingly, Bretz’ evidence that both parties treated the August 23 letter as an offer was admissible and there is a genuine issue of fact to be resolved.
II. ESTOPPEL
I also believe that there is a genuine issue of fact whether PGE is equitably estopped from raising the statute of frauds defense. Bretz produced evidence that PGE told him, by telephone, that its August 23 letter was an offer that would become a contract upon Bretz’s acceptance. The memorandum of the August 25th telephone conference indicates that Bretz asked “is this deal done now so I know where I stand?” PGE replied “Yes”. There is no evidence that PGE informed Bretz that PGE intended to retain the right to revoke its offer prior to receipt of Bretz’ acceptance.3 Thus, there is a genuine issue of fact whether the fourth element for estoppel under Montana law has been met. “[T]he conduct must be done ... at least with the expectation, that it will be acted upon by the other party, or under circumstances that it is both natural and probable that it will be so acted upon.” Smith v. *417Krutar, 153 Mont. 325, 457 P.2d 459, 463 (1969).
There is a factual issue whether PGE should reasonably have expected Bretz to rely on its oral representations that there would be a binding contract when Bretz indicated his acceptance. There is also a factual question whether it was both natural and probable that PGE’s conduct would “be acted upon.” In my view, one natural and probable result of entering into a contract for the sale of a coal mine is that the purchaser will negotiate with third parties for the sale of coal. PGE failed to show that there was no genuine issue of fact regarding Bretz’ estoppel claim. Thus, I would reverse the summary judgment on that ground also.
. The Montana parol evidence rule “does not exclude other evidence of the circumstances under which the agreement was made or to which it relates ... or other evidence to explain an extrinsic ambiguity or to establish illegality or fraud." Mont.Code Ann. § 28-2-905(2) (1987).
. The majority asserts that the letter refers to another commitment PGE had for the sale of stock, from which PGE would have to free itself before it could sell the stock to Bretz.. In fact the letter refers to a commitment from another buyer for the purchase of the stock, and reflects no commitment on the part of PGE. The majority also asserts that “[t]he letter plainly states that PGE remained 'receptive to an offer’ from Bretz" (emphasis added), erroneously indicating that PGE’s statement did not reflect a change from its position during the earlier negotiations. The letter does not use the word "remain".
. As the majority points out, the memorandum also indicates PGE said "Send over something in writing ... when we have it you have the mine on the deal we have made.” Although this statement creates an ambiguity, it does not eliminate the factual issue whether PGE’s conduct as a whole made Bretz’ reliance reasonable.