This is the main organisation. It gives loan in the form of loan not in the form of debt securitization. In this party, we can include RBI or SBI.
2nd Party : Special Purpose Vehicle
Special Purpose vehicle are that party who gets loan or pool of loan from originator and convert it in marketable securities. After converting it in marketable securities or papers or Demat, it will become debt securitized. Now, SPV will sell it in the money or any other financial market. These parties include private banks and other private financial institution which you can find their office in your local city.
3rd Party : Qualified Institutional Buyers
Now SPV advertises for his debt securitization product. But they did not sell to all. SPV sells to those who clear its condition. All these parties are called QIB.
Suppose, SBI finds 10 SPV and gave loan of Rs. 200 Crores. Now, 10 SPV converts this Rs. 200 loan in the form of debt securitization and sells to different qualified buyers. These buyers may be 1000 or 100000. One of the best benefit of debt securitization is to reduce risk. If SBI gives Rs. 200 crores to one party. It may be risky. But to give 10 SPV is less risky. For SPV, market instruments are also less risky to give 100000 persons.