Hi.. I'm doing a research about mortgage backed securitization issued by mortgage companies and I would like to ask about :
1. How long the maturity of these securities could be ?
2. How securitization can positively affect the market ?
3. Are there any financial institutions that guaranteed these securities?

Terms/maturity will vary, depending on the packaged units.
Securitization, or simply put, bonds that have real estate backing them can allow favorable borrowing rates in the bond markets. MBS increase liquidity, by freeing up the mortgage companies to expand their portfolios after shedding existing holdings. Not sure who offers backing, but you can check with CMHC.