(a) [General rule: perfection by filing.]
Except as otherwise provided in subsection (b) and Section 9-312(b), a financing statement must be filed to perfect all security interests and agricultural liens.
(b) [Exceptions: filing not necessary.]
The filing of a financing statement is not necessary to perfect a security interest:
(1) that is perfected under Section 9-308(d), (e), (f), or (g);
(2) that is perfected under Section 9-309 when it attaches;
(3) in property subject to a statute, regulation, or treaty described in Section 9-311(a);
(4) in goods in possession of a bailee which is perfected under Section 9-312(d)(1) or (2);
(5) in certificated securities, documents, goods, or instruments which is perfected without filing or possession under Section 9-312(e), (f), or (g);
(6) in collateral in the secured party's possession under Section 9-313;
(7) in a certificated security which is perfected by delivery of the security certificate to the secured party under Section 9-313;
(8) in deposit accounts, electronic chattel paper, investment property, or letter-of-credit rights which is perfected by control under Section 9-314;
(9) in proceeds which is perfected under Section 9-315; or
(10) that is perfected under Section 9-316.
(c) [Assignment of perfected security interest.]
If a secured party assigns a perfected security interest or agricultural lien, a filing under this article is not required to continue the perfected status of the security interest against creditors of and transferees from the original debtor.