"The U.S. shadow banking sector is alive and well, growing at a fast pace and remains opaque," MarketWatch's Greg Robb writes, citing top economists at the University of Chicago, Harvard and the Fed.

Why it matters: The sector might not cause the next downturn, but Dallas Fed president Robert Kaplan says he's worried it could be “an accelerant” to a recession that does come.

What's happening: "The shadow banking sector, now called by the more polite term 'private debt market’ has roughly tripled in size over the past few years and one estimate puts the size around $1.2 trillion," Robb writes from the American Economics Association conference in San Diego.

  • One big risk of the shadow banking sector is that investors can demand their money at any time. That could lead to a run on their assets, according to Jeremy Stein, a former Federal Reserve governor and a finance expert at Harvard.

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9 mins ago - World

Trump announces new Iran sanctions in effort to maintain international arms embargo

Photo: Anna Moneymaker-Pool/Getty Images

President Trump signed an executive order on Monday that would impose sanctions on any person or entity that contributes to the supply, sale, or transfer of conventional arms to or from Iran or is engaged in providing training and financial support related to those weapons.

Why it matters: The executive order is the first step by the Trump administration to put teeth into its claim that international sanctions on Iran were restored over the weekend, one month after the U.S. initiated the "snapback" process under a United Nations Security Council resolution.

Exclusive: Conservative group launches $2M Supreme Court ad

Screengrab of ad, courtesy of Judicial Crisis Network.

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The big picture: "Follow Precedent," previewed by Axios, is one of the first national and cable television ads to run following Justice Ruth Bader Ginsberg's death Friday.

Updated 25 mins ago - Politics & Policy

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CDC Director Robert Redfield. Photo: Anna Moneymaker/Pool/Getty Images

The CDC has removed new guidance that acknowledged airborne transmission of the coronavirus, posting in a note on its website that the guidance was only a draft and had been published in error.

Why it matters: The initial update — which was little noticed until a CNN story was published Sunday — had come months after scientists pushed for the agency to acknowledge the disease was transmissible through the air. The CDC previously said that close person-to-person contact was the bigger concern, and the language has been changed back to erase the warning about airborne transmission.