JPM Net in action

In her letter, Warren correctly notes that neither September's tax payment deadlines, nor the Treasury auction settlements - which many claimed catalyzed the surge in the overnight repo rate from 2% to 10%, were a surprise; it also wasn't a surprise that the Fed's reserve shrinkage, i.e. Quantitative Tightening, which were on "autopilot" as recently as last December, surprised Wall Street professionals and were not "the type of unforeseeable circumstance that would have rattled markets so suddenly."
Instead, what Warren - who very well may be president of the US in just over a year's time - indirectly suggests, and which we thoroughly agree with, is that one bank - which on October 2 we disclosed was JPMorgan - deliberately yanked cash from money markets in order to "suddenly" tighten financial conditions, in the process causing a funding crisis and and sparking the Sept 16 repocalypse (which "coincidentally" took place on the 11th anniversary of the Lehman collapse). This is what Warren said:

I am also concerned that, "Big U.S. banks are using the recent chaos in short-term funding markets as an opportunity to pressure the Federal Reserve to ease liquidity requirements they have long despised," and that the FSOC might support these efforts. These rules were designed to ensure that banks have enough cash on hand to meet their obligations in the event of another market crash."

The primary dealership has been weakened via the sandbox effect.

JPM is no an entire liquidity net unto themselves  for the wealthy clients.  The JPM trading staff acts like trusted ledger via one's JPM account. This is fast enough to support the bearer asset concept, as long as jPM board is reasonably honest about front running.

 Sandbox naturally cancels arbitrage moments, and the primary dealership system is nothing but.  JPM Net is a one to one exchange between the Treasury curve and some complete representation of global investments. Th Fed system is still a two step contract with the Swift edger always imposing.  The technology of the former supports better liquidity than the later, via automatic price discovery.

Sandbox effect is real, it is one of those thousand year technology jumps, Morse and Moore's law teaming up with run time option pricing. The tendency toward the fastest to discovery in closing arbitrage moments, the technology requiring digital bearer assets..

JPM has to compete with Bitcoin as an asset exchange mechanism, then it compete with Telegram and its anonymous trading support. Then it deals with shadow lenders who are increasingly automated, risk adjusted and profitable.  JPM made JPM Net, not consciously, but as a naturally side effect of casting about in these waters.  It is popping up, it is internally starting to find and solve arbitrage moments as new trading options can be constructed and opened.