What you need to know on Wall Street today

Welcome to Finance Insider, Business Insider’s summary of the top stories of the past 24 hours.

How healthy is the US job market, really?

This remains a major question among economists and Federal Reserve officials, many of whom believe a historically low 4.3% jobless rate means the US economy is at, or near, what experts call “full employment.”

Just last week, Wall Street cheered the July jobs report showing a robust gain of 209,000 net new jobs, sending stocks to record highs. Some central bankers, however, argue that low inflation and the absence of wage growth cast doubt on the notion of a fully healed labour market. Two top Fed policymakers this week spoke out against the prospect of additional interest-rate increases.

One trend could be especially ominous: a spike in the number of Americans taking multiple jobs has effectively reversed a two-decade decline.

In related news, this map shows how much the highest-paid women in every US state make compared to men — the difference in their salaries is stunning. And credit-card debt in the US rose in June to surpass the peak set just before the 2008 financial crisis.

In Wall Street news, Davidson Kempner, one of the largest hedge fund firms in the world, is betting big on mega-deals. And Jonathan Yalmokas, a top Wall Street executive who specialises in servicing hedge funds, has changed his mind about joining RBC Capital Markets and is headed to Cantor Fitzgerald instead.

In markets news, trouble is lurking under the surface of the stock market, according to Business Insider’s Joe Ciolli. Investors are seeking an edge by targeting “unknown” stocks. Traders are fleeing the year’s hottest investment. And Japan’s political turmoil should make investors nervous, according to PIMCO.

Hedge funders are receiving death threats after shorting Chinese companies in Hong Kong. And China has suddenly stopped buying foreign property.

In other news, investors are reportedly eating up Tesla’s junk-bond sale. Delta’s replacement for the jumbo jet has arrived. And JetBlue is making a major investment to fix airlines’ awful customer service crisis.

Lastly, go inside a New York billionaire wedding where guests included Jennifer Lopez and the Clintons.