Earlier quoted context omitted.
The Fed can buy mortgage backed securities like they have done since they've started quantitative easing. The Fed has purchased Apple bonds. This is in addition to US Treasuries. My original comment was a mechanics related comment in which liquidity (credit + cash) pushes up asset prices and not rates (although there's high correlation especially in the past 20 years in the US). This is based on my understanding of R…
The volume of mortgage backed securities is based on the volume of loans that people take. At higher interest rates, people take out fewer and smaller loans. The Fed buying up more MBS would put downwards pressure on interest rates, which would be diametrically opposed to their goal (in your scenario) of maintaining high interest rates. There is a correlation between liquidity and rates, but it's an inverse correlati…
My example of the Fed with high interest rates and a lot of QE was a way to see where our disagreement would appear. It's similar to the great recession where there were interest rates lower than they are now, but because the private sector wasn't extending credit (less Cash + Credit); there didn't appear to be any asset bubbles.
The volume of mortgage backed securities is based on who can and want to get loans. During the great recession it was hard to qualify for a mortgage even though many people wanted to do so.