ON REHEARING
McFADDEN, Justice.The previous opinion in this ease is withdrawn and this opinion is hereby substituted.
This appeal arises from an action to recover stock certificates pledged to defendant-appellant Idaho Bank and Trust Company (hereinafter IB&T). The district court granted summary judgment in favor of plaintiff-respondent L. Katharine Ogilvie (hereinafter respondent Ogilvie), holding that the pledge of the stock certificates was invalid and that IB&T acquired no rights by the pledge. The judgment is affirmed.
Stock certificates representing 629 shares of common stock of Idaho First National Bank were originally purchased by respondent Ogilvie. At her request, the certificates were reissued to respondent Ogilvie and her son, Richard R. Ogilvie, as follows:
1. Two hundred eighty-eight shares were issued between May 5,1956, and January 21,1965, in the following language: “L. KATHARINE OGILVIE & RICHARD R. OGILVIE, JT. TEN.”
2. Three hundred forty-one shares were issued between March 4, 1968, and January 18, 1973, in the following language: “L. Katharine Ogilvie & Richard R. Ogilvie. As joint tenants with right of survivorship and not as tenants in common.”
Respondent Ogilvie states in her deposition, which was introduced in the proceeding below, that she placed both names on these certificates, “because I thought I just might die someday and I wanted them to go to him.” She states further that while the dividends were paid to her, additional issues of stock, either by way of stock splits or stock dividends, were issued in both names. She kept the stock certificates in a metal file box in her home until she became ill and, following hospitalization, was moved to a Boise nursing home. Her sister then took possession of her belongings, including the stock certificates. Richard Ogilvie thereafter somehow acquired possession of the shares from his aunt, but without respondent Ogilvie’s knowledge or consent.
On November 20, 1974, Richard Ogilvie pledged these stock certificates to IB&T as collateral for a $14,795.50 personal loan. Idaho Bank and Trust did not register this transfer with Idaho First National Bank nor did it receive new, reissued or re-registered stock certificates from Idaho First National Bank.
In conjunction with the loan, IB&T required the signatures of both Richard Ogilvie and respondent Ogilvie on the stock power indorsing the stock certificates. The signatures of respondent Ogilvie appearing on these documents were forged.
*363The loan became due on February 18, 1975, and has since been delinquent. Richard Ogilvie died on March 1, 1975. Idaho Bank and Trust then commenced foreclosure proceedings on the certificates. Respondent Ogilvie, in response, initiated the present action to recover the stock certificates from IB&T. The district court granted summary judgment for respondent Ogilvie, holding that there was no evidence of a valid intervivos gift of the stock certificates to Richard Ogilvie. The district court held that since Richard Ogilvie acquired no interest in the certificates that might be encumbered by a pledge of the certificates, IB&T acquired no interest in the certificates. This appeal is from that judgment.
The issue on appeal is whether, by obtaining a pledge of the certificates from Richard Ogilvie, IB&T acquired any interest in these stock certificates, and if so, to what extent.
Notwithstanding Idaho statutory and common law principles concerning gifts and the creation of joint tenancies, transfers of investment securities are governed by the Idaho Uniform Commercial Code — Investment Securities (hereinafter Article 8). I.C. §§ 28-1-105(2), -8-102(l)(b). However, where Article 8 is silent as to the applicable law, our disposition is governed by principles of law and equity supplementing the provisions of the Uniform Commercial Code. I.C. § 28-1-103.
I
UNIFORM COMMERCIAL CODE — INVESTMENT SECURITIES
The stock certificates involved in this case are “securities” as that term is defined by Article 8. “A ‘security’ is an instrument which is . in . . . registered form; and is of a type commonly dealt in upon security exchanges . . [and] is issued or dealt in as a medium for investment; and is divisible into a class or series of instruments; and evidences a share, participation or other interest in property or evidences an obligation of the issuer.” I.C. § 28-8-102(l)(a).
Under Article 8, IB&T, by virtue of Richard Ogilvie’s pledge of the stock certificates, is a purchaser of securities. A “purchaser” is defined by I.C. § 28-1-201(33) as “a person who takes by purchase.” Under I.C. § 28-1-201(32), “ ‘purchase’ includes taking by . . . pledge, . . . gift or any other voluntary transaction creating an interest in property.” The facts are uncontroverted that Richard Ogilvie voluntarily pledged the stock certificates to IB&T, thereby conferring purchaser status upon IB&T.
Under these facts, IB&T also enjoys the preferred status of a “bona fide purchaser.” See I.C. § 28-8-301(2). Idaho Code § 28-8-302 provides: “A ‘bona fide purchaser’ is a purchaser for value in good faith and without notice of any adverse claim who takes delivery of a security . in registered form . . indorsed to him . .” As has been indicated, IB&T is a “purchaser” under I.C. § 28-1-201(32), (33). “Value” includes the act of extending credit. I.C. § 28-l-201(44)(a). Under Article 8, “good faith” and “without notice” mean that the person extending credit acts honestly in conducting the transaction and has neither actual knowledge, nor, from all the facts and circumstances, should have known that an adverse claimant asserts rights in the pledged collateral. I.C. § 28-1-201(19), (25). In the instant case, there is no evidence that anyone other than Richard Ogilvie or respondent Ogilvie claim any interest in the securities. Although IB&T could have protected itself from a forgery, I.C. § 28-8-312, there is no evidence suggesting that IB&T knew or should have known that respondent Ogilvie claimed rights to the pledged collateral because her signature was forged. Therefore, by extending credit IB&T became a bona fide purchaser of the pledged securities after receiving delivery of the shares pursuant to the pledge agreement. (A)
RESPONDENT OGILVIE’S FORGED INDORSEMENT
Once the logical connection between different definitional sections of the Idaho *364Uniform Commercial Code is made and such definitional matters understood, I.C. §§ 28-8-301 to -8-320 provide a relatively simple method for resolving claims between competing claimants in investment securities.
As a general rule, a bona fide purchaser, upon receiving delivery of an investment security, prevails against all adverse claimants. I.C. § 28-8-301(2). A bona fide purchaser is, therefore, a favored sub-class of purchasers prevailing over all claimants, including the true owner of the security. I.C. § 28-8-301(1).
To this broad statement is added the exception contained in I.C. § 28-8-311(a), providing that in cases of forged indorsements, a bona fide purchaser prevails against the true owner only if he has received new, reissued or re-registered securities from the issuer.1 Under I.C. § 28-8-311(a), the true owner of an investment security, with certain exceptions not herein applicable, may assert the ineffectiveness of an “unauthorized indorsement” appearing on pledged securities against a bona fide purchaser, unless the bona fide purchaser has received new, reissued or re-registered securities from the issuer. The “unauthorized indorsement” referred to in I.C. § 28-8-311 “means one made without actual, implied or apparent authority and includes a forgery.” I.C. § 28-1-201(43). Thus when reconciling the broad protection extended a bona fide purchaser in I.C. § 28-8-301(2) with the protection afforded the true owner of the securities in I.C. § 28-8-311(a), as between the owner and a bona fide purchaser relying on a forged indorsement of pledged securities, priority is given the owner, unless the bona fide purchaser also received reissued stock certificates from the issuer prior to receiving notice of the owner’s adverse claim. See Folk, Article 8: Investment Securities, 44 N.C.L.Rev. 654 (1966); Folk, Some Problems Under Article 8 of the Uniform Commercial Code, 5 Ariz.L.Rev. 193 (1964); Guttman, Article 8 — Investment Securities, 17 Rutgers L.Rev. 136 (1962).
This priority extended to the true owner of forged stock certificates includes the right to reclaim possession of the securities from a bona fide purchaser:
If the transfer is wrongful because of an unauthorized endorsement, the owner may also reclaim or obtain possession of the security or new security even from a bona fide purchaser if the ineffectiveness of the purported indorsement can be asserted against him under the provisions of this chapter on unauthorized indorsements [section 28-8-311].
I.C. § 28-8-315(2).
The record is uncontradicted that Richard Ogilvie forged respondent Ogilvie’s indorsement to the promissory note, pledge instrument, loan purpose statement and stock power in pledging the securities to IB&T as collateral for his loan. Since IB&T did not receive new, reissued or re-registered securities from Idaho First National Bank, it cannot assert rights in the securities against respondent Ogilvie by virtue of the forged indorsement.
(B)
RICHARD OGILVIE’S INDORSEMENT
Richard Ogilvie’s own indorsement of the promissory note, pledge instrument, loan purpose statement and stock power, however, was not forged. The issue remains whether IB&T acquired an interest and if so, to what extent, in the securities by virtue of Richard Ogilvie’s delivery, indorsement and pledge of the stock certificates.
While the record is uncontroverted that respondent Ogilvie initially did not give Richard Ogilvie possession of the stock cer*365tificates, it is also uncontroverted that she, as the sole owner of the stock certificates, later indorsed and delivered them to Idaho First National Bank and requested that it reissue the certificates to herself and Richard Ogilvie as joint tenants. This presents the issue of whether respondent Ogilvie’s voluntary parting with control, indorsement and delivery of the stock certificates to Idaho First National Bank with instructions to list Richard Ogilvie as a joint tenant give Richard Ogilvie an enforceable interest in the securities under Article 8.
It is important to note that two transfers of investment securities are involved in this case: the first concerns a transfer from respondent Ogilvie to Richard Ogilvie when the stock certificates were indorsed and delivered to Idaho First National Bank with directions to reissue the certificates to Richard Ogilvie as a joint owner; the second involves a transfer from Richard Ogilvie to IB&T. No question is raised concerning the second transfer from Richard Ogilvie to IB&T and, therefore, whatever interest Richard Ogilvie obtained or possessed was transferred to IB&T. The court’s inquiry, thus, focuses on the first transfer from respondent Ogilvie to Richard Ogilvie via Idaho First National Bank to determine what rights, if any, he obtained from respondent Ogilvie that he could thereafter pledge to IB&T.
A “purchaser” is one who takes by purchase, I.C. § 28-1-201(33); “purchase” includes taking by issue or reissue. I.C. § 28-1-201(32). Thus, Richard Ogilvie became a purchaser of the stock certificates when Idaho First' National Bank reissued the certificates to respondent Ogilvie and Richard Ogilvie as joint tenants.
Under I.C. § 28-8-309, a transfer of an investment security to a purchaser requires both an indorsement and a delivery of the security: “An indorsement of a security * * * does not constitute a transfer until delivery of the security on which it appears or if the indorsement is on a separate document until delivery of both the document and the security.” This “delivery” requirement is explained as being a voluntary parting with control of the securities, I.C. § 28-1-201(14), and occurs when the purchaser or someone on his behalf acquires actual possession of the indorsed security. I.C. § 28-8-313(l)(a).
While the requirement of physical delivery contained in Article 8 may serve a valid evidentiary purpose in the case of a sole owner, where, as here, there is more than one listed owner, the requirement that the new owners personally receive physical possession of the stock certificates to constitute a valid transfer is not applicable because both joint tenants cannot enjoy possession simultaneously. Robison v. Fickle, 340 N.E.2d 824 (Ind.Ct.App. 1976). This result is especially appealing because possession by one co-owner is deemed possession by all. Washington County Irrigation Dist. v. Talboy, 55 Idaho 382, 43 P.2d 943 (1935); Kinney v. Ewing, 83 N.M. 365, 492 P.2d 636 (N.M. 1972); Frey v. Wubbena, 26 Ill.2d 62, 185 N.E.2d 850 (1962); In re Estate of Paulson, 219 N.W.2d 132 (N.D. 1974). Moreover, since possession alone, without the other co-owner’s indorsement will not result in a valid transfer of the entire interest, I.C. §§ 28-8-308(3)(e), -8-309, no purpose is served by requiring physical delivery to Richard Ogilvie to constitute a transfer of an investment security. See Frey v. Wubbena, 26 Ill.2d 62, 185 N.E.2d 850 (1962); Robison v. Fickle, 340 N.E.2d 824 (Ind.Ct.App. 1976); Kintzinger v. Millin, 254 Iowa 173, 117 N.W.2d 68 (1962); Marans v. Newland, 141 Mont. 32, 374 P.2d 721 (1962); In re Estate of Paulson, 219 N.W.2d 132 (N.D. 1974); Buresh v. First Nat’l Bank of Oregon, 262 Or. 104, 496 P.2d 913 (1972); Manning v. United States Nat’l Bank of Portland, 174 Or. 118, 148 P.2d 255 (1944); Henderson v. Tagg, 68 Wash.2d 188, 412 P.2d 112 (1966). Unquestionably, respondent Ogilvie could not have transferred full ownership in the shares to a third party during Richard Ogilvie’s lifetime without obtaining his indorsement of the jointly owned stock certificates. I.C. § 28-8-308(3)(e). This court therefore holds that respondent Ogilvie’s voluntary parting with control, delivery and indorsement of the *366stock certificates to Idaho First National Bank satisfied the delivery and indorsement requirements of I.C. § 28-8-309 and gave Richard Ogilvie some interest in the stock certificates. This interest could thereafter be conveyed to a bona fide purchaser accepting a pledge of the securities. Our holding is in conformity with the dictates of Article 8 extending foremost protection to a bona fide purchaser of investment securities. I.C. § 28-8-301(2).
Under I.C. § 28-8-301(3), Richard Ogilvie’s interest was limited to that of a joint tenant of stock certificates: “A purchaser of a limited interest acquires rights only to the extent of the interest purchased.” Joint ownership with right of survivorship is a recognized form of ownership of investment securities under Article 8. I.C. § 28-8-308(3)(e). Similarly, a pledge of stock certificates is a recognized method of perfecting a security interest. I.C. § 28-9-302; 1.C. § 28-9-305. However, the attributes of ownership held by a joint tenant in investment securities is not addressed by the Uniform Commercial Code, except as provided by I.C. § 28-1-103: “Unless displaced by the particular provisions of this act, the principles of law and equity * * * shall supplement its provisions.”2 Therefore, to this extent, the court’s disposition is controlled by applicable common law principles governing joint tenancies.
II
JOINT TENANCY
Initially, it is important to note the limited scope of the court’s inquiry of common law principles applicable to jointly owned stock certificates. A valid transfer of investment securities into joint ownership occurs when the “indorsement” and “delivery” requirements of I.C. § 28-8-309 are satisfied. See Part 1(B) supra. The issue thus viewed, the court need not decide whether a valid gift inter-vivos was effected and whether a valid joint tenancy was created. This was satisfied when the stock certificates were indorsed and delivered to the issuer with instructions to list the purchaser as a joint tenant. I.C. § 28-8-309. The court’s inquiry is instead directed toward the competing rights of respondent Ogilvie and a third party, IB&T, who claims possessory rights by virtue of Richard Ogilvie’s pledge of jointly owned stock certificates.
Idaho continues to recognize joint tenancies between two persons as a valid and enforceable means of concurrent ownership of property, whether real, personal, tangible or intangible. I.C. § 55-104. A distinguishing incident of joint tenancy is the right of survivorship, whereby the death of one joint tenant terminates the joint tenancy and vests complete title in the surviving joint tenant. 4 G. Thompson, Real Property § 1779 (1961). A joint tenancy, however, may be terminated prior to the death of one of the joint tenants by any act of the joint tenants which destroys one or more of the essential common law unities of interest, title, time and possession, 2 American Law of Property § 6.2 (A. Casner ed. 1952); W. Burby, Real Property § 94 (3d ed. 1965); 4 G. Thompson Real Property § 1779 (1961); 48 C.J.S. Joint Tenancy § 4 (1947). Because of the right of survivorship, debts secured by jointly owned property by a debtor joint tenant are not enforceable against the joint tenancy property after the death of the debtor joint tenant, unless one or more of the essential unities was destroyed prior to the joint tenancy’s termination by death, and then only to the extent of the debtor joint tenant’s interest. W. Burby, Real Property § 94 (3d ed. 1965); 4 G. Thompson, Real Property § 1780 (1961); 20 Am.Jur.2d Cotenancy and Joint Ownership § 108 (1965).
The remaining issue, therefore, is whether the joint tenancy in the stock certificates was severed prior to its termination on Richard Ogilvie’s death. If it was severed, Richard Ogilvie and respondent *367Ogilvie acquired equal one-half interests in the stock certificates as tenants in common and IB&T could foreclose on Richard Ogilvie’s one-half interest. However, if no severance occurred, IB&T would have no enforceable interest in the stock certificates because title to the jointly owned property vested solely in respondent Ogilvie at the instant of Richard Ogilvie’s death because of the right of survivorship.
A pledge is a security device whereby possession of personal property is transferred to the creditor as security for the debt. Isaak v. Journey, 52 Idaho 392, 15 P.2d 1069 (1932). The pledgee obtains merely a possessory lien against the property pledged. MacDonald v. Pacific Nat’l Bank of San Francisco, 66 Cal.App.2d 357, 152 P.2d 360 (1944); First State Bank of Audubon, Iowa v. Collins-Dietz-Morris Co., 190 Okl. 409, 123 P.2d 957 (1941); Howick v. Bank of Salt Lake, 28 Utah 2d 64, 498 P.2d 352 (1972). In this state, liens do not transfer title to the property that is pledged. I.C. § 45-109. The common law unity of title was not, therefore, destroyed by Richard Ogilvie’s pledge of the stock certificates. See People v. Nogarr, 164 Cal.App.2d 591, 330 P.2d 858 (1958) (mortgage by one joint tenant of jointly owned realty does not destroy unity of title in a state following lien-theory of mortgages); D.A.D., Inc. v. Moring, 218 So.2d 451 (Fla.App. 1969) (action to foreclose mortgage on realty executed by one joint tenant is not enforceable after death of debtor joint tenant); Hyland v. Standiford, 253 Iowa 294, 111 N.W.2d 260 (1961) (pledge of stock certificates as security for a loan does not sever the joint tenancy).
IB&T argues that Richard Ogilvie’s pledge of the stock certificates destroyed the common law unity of possession and resulted in a severance of the joint tenancy because a pledge, by definition, requires that the pledgee receive physical possession of the collateral. This argument is unpersuasive. The unity of possession essential to the existence of a joint tenancy means that each joint tenant is entitled to the use and enjoyment of the whole property, as if a sole owner, subject to the other joint tenants’ equal and undivided rights of possession. 4A R. Powell, Real Property §§ 603, 617 (1977), 4 G. Thompson, Real Property § 1777 (1961). Appellant’s argument ignores the fact that joint tenants may contractually transfer possession of joint tenancy property without effecting a severance of the joint tenancy. A lease, or other similar conveyance transferring possession of joint tenancy property to a third party, executed by all the joint tenants does not sever a joint tenancy, nor will severance result when less than all joint tenants execute a lease of joint tenancy property. See generally Annot., 49 A.L. R.2d 797 (1956). In most jurisdictions, a lease given by less than all the joint tenants allows the lessee to occupy and possess the joint tenancy property, subject to the nonparticipating joint tenants’ rights of possession. Annot., 49 A.L.R.2d 797 (1956). Similarly, a joint pledge of stock certificates to secure a joint liability of the joint tenants does not result in a severance of a joint tenancy in stock certificates, despite the pledgee’s possession of the stock certificates. Hyland v. Standiford, 253 Iowa 294, 111 N.W.2d 260 (1961). In Swartzbaugh v. Sampson, 11 Cal.App.2d 451, 54 P.2d 73 (1936), the court said:
It has also been held that one joint tenant in possession of personal property may pledge his interest in the property to another; that the pledgee’s rights are valid to the extent of the pledgor’s interest; that each joint tenant has an equal right of possession and so the pledgee has the same right of possession that the pledgor had * * *.
Id. 54 P.2d at 77 (citing with approval Frans v. Young, 24 Iowa 375 (1868)). The court therefore holds that the common law unity of possession was not destroyed when IB&T obtained physical possession of the jointly owned stock certificates.
Therefore, no severance of the jointly owned stock certificates occurred before Richard Ogilvie’s death. IB&T took as security the interest of but one of two joint tenants. This interest extinguished when Richard Ogilvie failed to survive respondent Ogilvie. IB&T thus has no interest in the *368stock certificates that is now enforceable against respondent Ogilvie.
The judgment of the district court is affirmed with instructions to enter appropriate orders transferring possession of the stock certificates to respondent Ogilvie as the surviving joint tenant. Costs to respondent Ogilvie.
DONALDSON, J., concurs. SHEPARD, C. J., concurs in the result.. 28-8-311. Effect of unauthorized indorsement. — Unless the owner has ratified an unauthorized indorsement or is otherwise precluded from asserting its effectiveness
(a) he may assert its ineffectiveness against the issuer or any purchaser other than a purchaser for value and without notice of adverse claims who has in good faith received a new, reissued or re-registered security on registration of transfer; .
. The competing rights of a pledgee and nonparticipating joint tenant of stock certificates pledged by a debtor joint tenant are also not addressed by the Idaho Uniform Commercial Code — Secured Transactions, except as provided by I.C. § 28-1-103.