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Over the next decade, low growth , low inflation and low yields could push returns for the classic US portfolio — 60% stocks and 40% bonds — down toward their lowest point in a century. That's right: a century.

Strategists at Morgan Stanley see US stocks and US Treasuries returning 4.9% and 2.1% each year during that timeframe, according to research published this weekend. The traditional US portfolio would therefore return just 2.8% annually — half the average performance over the past 20 years.

"Investors will need to accept much higher volatility to eke out small incremental units of return," strategists including Serena Tang, executive director of cross-asset strategy, told clients. Investors will likely opt for fewer government bonds, favoring high-quality credit instead.

McDonald's has fired its CEO

McDonald's has ousted CEO and president Steve Easterbrook after the company's board determined he violated corporate policy.

Easterbrook, who became CEO in 2015, "demonstrated poor judgment involving a recent consensual relationship with an employee," McDonald's said in a statement.

Stepping in: Easterbrook will be replaced in both roles by Chris Kempczinski, effective immediately, my CNN Business colleague Danielle Wiener-Bronner reports. Kempczinski was most recently president of McDonald's USA.

"Given the values of the company, I agree with the board that it is time for me to move on," Easterbrook said in an email to employees. "Beyond this, I hope you can respect my desire to maintain my privacy."

What it means: Easterbrook had been leading McDonald's in an aggressive modernization plan. During his tenure, the company rapidly remodeled stores to include digital menu boards, and acquired AI companies to improve the drive-thru experience, per Danielle.

Shares have nearly doubled since he started in the role:

More from Danielle: "The company had also committed to its core menu offerings, abandoning its craft sandwiches and shrinking late night meals to increase efficiency. In a complicated but successful initiative, the company started selling fresh beef quarter pounders."

But there's also been some tension with franchisees. McDonald's franchise operators formed an association for the first time in 2018. They have been pushing for some changes, like the addition of a premium chicken sandwich to the menu.

Investor insight: Despite its recent winning streak, McDonald's shares fell last month after the company missed expectations for the third quarter, and its stock is down another 2.5% in premarket trading Monday. Kempczinski doesn't have an easy job ahead.

Under Armour is under US investigation

Under Armour's accounting practices are under investigation in the United States, heaping pressure on the struggling company as it seeks to reverse years of lackluster sales, my CNN Business colleague Charles Riley reports.

What happened: The sportswear maker acknowledged in a statement Sunday that it faces probes from the US Department of Justice and the US Securities and Exchange Commission.

"The company began responding in July 2017 to requests for documents and information relating primarily to its accounting practices and related disclosures, and the company firmly believes that its accounting practices and disclosures were appropriate," an Under Armour spokesperson said.

Under Armour UA Investor insight: Shares indropped 15% premarket to trade near $17.90. The stock had been trading above $50 per share as recently as late 2015. Under Armour is scheduled to report its third quarter results before the opening bell on Monday.

The Wall Street Journal was first to report on the investigations into the company's accounting practices. According to the Journal, the DOJ is conducting a criminal inquiry into whether Under Armour shifted sales from quarter to quarter to make the company appear healthier. The agency declined to comment to CNN.

Leadership shakeup: Under Armour announced last month that founder Kevin Plank is stepping down as CEO. He will be replaced by chief operating officer Patrik Frisk on January 1. The shuffle comes after the company suffered from weaker sales, losing ground to rivals including Nike and Adidas.

Up next

Earnings season is winding down, but it's not over yet. Ryanair and Under Armour report results before US markets open. Marriott, Uber, Groupon, Hertz, Shake Shack and The RealReal follow after the close.

Also today:

US factory orders for September arrive at 10 a.m. ET.

Coming tomorrow: The ISM Non-Manufacturing Index will shine a light on the health of the US services sector.