The Fed is lending against stocks and corporate bonds

The Fed already offered its primary dealers short-term cash loans secured by Treasuries, in “repurchase agreements” meant to keep interest rates under control. But with this offering, it will lend cash against securities such as equities, corporate bonds, municipal bonds, asset-backed securities and commercial paper.
https://www.barrons.com/articles/follow-the-consumer-and-stick-with-these-staples-through-coronavirus-crisis-advises-jefferies-51584361556

To be clear, the Fed is only lending to primary dealers.  Who are these elite members?  Here is the list:

Amherst Pierpont Securities LLC

Bank of Nova Scotia, New York Agency

BMO Capital Markets Corp.

BNP Paribas Securities Corp.

Barclays Capital Inc.

BofA Securities, Inc.

Cantor Fitzgerald & Co.

Citigroup Global Markets Inc.

Credit Suisse AG, New York Branch

Daiwa Capital Markets America Inc.

Deutsche Bank Securities Inc.

Goldman Sachs & Co. LLC

HSBC Securities (USA) Inc.

Jefferies LLC

J.P. Morgan Securities LLC

Mizuho Securities USA LLC

Morgan Stanley & Co. LLC

NatWest Markets Securities Inc.

Nomura Securities International, Inc.

RBC Capital Markets, LLC

Societe Generale, New York Branch

TD Securities (USA) LLC

UBS Securities LLC.

Wells Fargo Securities, LLC

Source:  https://www.newyorkfed.org/markets/primarydealers

These companies can borrow at close to zero (the actual rate is 0.25% per year).  These are all effectively too big to fail.  They are a critical part of the funding mechanism for the Treasury.  When the Treasury needs dollars (and it will soon need more than a trillion for the latest bailout), it sells bonds to these primary dealers.  The primary dealers in turn are wholesalers and try to sell the bonds to pension funds, mutual funds, etc.  They also sell bonds to the Federal Reserve, which prints electronic dollars out of thin air to buy them.