Yes, HSBC would lose 900k. 900k loss is still better than having $1million of bad debt on your books and having S&P downgrade your credit rating. Also, most banks have convenants and ratios to manage, so having 900k wiped off their books isnt by choice.
remember, the loans bought by the SPV already are in default. Thats the whole point of HSBC selling them at a discount - the`re termed distressed debt.
My guessing is that these SPVs are highly leveraged with debt, so theres more upside for the equity holders. And the debt are probably tranched from senior, mezz to junior.
Actually, the above example is pretty much what happened to Japan and their super banks. They lent out loans to every tom & dick & harry, who inturn, used the $$$ to invest in real estate during the boom periods. During the period of bust, the japanese superbanks were left with nothing but bad debt on their books. They literally had to give away all their non performing loans for free even though alot of the loans were secured against the collateral bought.
Now that we are in a period of growth and real estate prices are going up, those SPVs which these distressed debt a few years back, are sitting on a goal mine.