USD 10 Trillion is a big number...

FT:  Crunch feared if collateral rules enforced
"New clearing regulations could suck in USD 10tn of safe assets...European parliamentarians this week debated plans to make safer the financial derivatives industry – an essential cog in the global economy – where the notional amounts outstanding on over-the-counter deals exceed USD 600tn. Regulators want more trades processed through transparent exchanges and cleared through “central counterparties”, back office institutions that stand between two parties in a trade, ensuring they are completed even if one side defaults...Regulators are pushing for non-centrally cleared trades to be backed by high levels of collateral, such as cash or government bonds. This is where the USD 10tn figure comes in. It is the amount of extra collateral that could be required according to estimates by the International Swaps and Derivatives Association...A separate IMF paper published last week by Manmohan Singh, ...puts the total additional collateral requirements resulting from regulatory changes at between USD 2tn and USD 4tn – less than the USD 10tn figure cited by the ISDA derivatives lobby, but still the same order of size, for instance, as the European Central Bank’s balance sheet...
But central banks are also, inadvertently, restricting collateral supplies. Mr Singh points out that bond purchases by the Swiss National Bank to prevent its currency’s appreciation “withdraw the best and most liquid collateral from the [neighbouring] eurozone”. Similarly, Fed purchases of US Treasuries and mortgage backed securities “could silo over USD 1tn additional good collateral in 2013”.

Quoting myself from a September 9, 2012  post

"My second thought was:   Centralized clearing has huge advantages in terms of risk mitigation.  However if some of our current economic problems are due to a shortage of high grade collateral (see link and abstract below) then the move to centralized clearing may also have some significant negative consequences as it further strains the supply of high quality collateral.

Ricard Cabellero - On the Macroeconomics of Asset Shortages

Abstract:   The world has a shortage of financial assets.  Asset supply is having a hard time keeping up with the global demand for store of value and collateral by households, corporations, governments, insurance companies, and financial intermediaries more broadly.  The equilibrium response of asset prices and valuations to these shortages has played a central role in global economic developments over the last twenty years.  The so-called "global imbalances", the recurrent emergence of speculative bubbles (which recently have transited from emerging market, to the dot-coms, to real estate, to gold...), the historically low real interest rates and associated "interest rate conundrum," and even the widespread low inflation environment and deflationary episodes in parts of the world, all fall into place once one adopts the asset shortage perspective. "

I am not sure that I would attribute as much as Cabellero does to the demand for high quality assets but there probably is something to his story.  And in case you were wondering, threatening to default on US Treasury debt does not help the situation.