A big worry is the future of securitization, a key mechanism of modern banking that enables banks to bundle loans and bonds into securities for sale to investors. This crucial market is moribund now that many of its creations have plunged in value. Some question when, or if, certain areas of securitization will revive.

Securitization, which works like a shadow banking system, has radically changed banking and the credit markets in recent years. Three decades ago, banks supplied $3 out of every $4 of credit worldwide. Today, because of securitization, that share has dropped to about $1 in $3.

Unless financial companies can securitize debt — which, in turn, depends on investors’ willingness to buy the bundled loans — credit will remain tight even if banks resume lending.