J.P. Morgan's Stephen Tusa on Monday downgraded General Electric shares to underweight from neutral and cut his 12-month price target to $5 from $6.

"We believe many investors are underestimating the severity of the challenges and underlying risks at GE, while overestimating the value of small positives, and with a 38% move in the stock year to date, and >50% cuts to forward fundamental FCF (free cash flow) anchors, we are cutting our [price target] and moving to" underweight, wrote Tusa in a note to clients.

General Electric shares fell about 6% Monday following Tusa's note.

Tusa first went negative on the stock in May 2016 before most on Wall Street. He then helped spur a turnaround in the shares in December when he upgraded the stock to neutral from underweight.

But the analyst has changed his view back to clearly negative:

"The driver of the downgrade is our view that the Street is significantly over projecting the bounce in FCF in the coming years, off levels that we calculate at zero currently, as Power/Renewables remains weak, GECS (GE Capital Services) will likely consume material cash for the foreseeable future, Aviation fundamentals, as per underlying FCF, are weaker than meet the eye, while lingering sector high leverage including entitlements leaves the company vulnerable to liquidity issues in the event of a recession, for which a potentially dilutive sale of the rest of Healthcare may be needed."

Once the nation's largest public company, General Electric has lost more than $200 billion in market value since 2017 as the American industrial company slowly unravels years of acquisitions under CEOs Jack Welch and Jeffrey Immelt. The company introduced former Danaher CEO Larry Culp as its leader on Oct. 1, tasked with improving cash flow and shaping the struggling conglomerate into a leaner company.

Though stakeholders have been largely happy with Culp's management, some were disappointed last month when he revealed that the company could burn as much as $2 billion more in cash than it makes in 2019.

"We have work to do in 2019, but we expect 2020 and 2021 performance to be significantly better," Culp said in a press release. Challenges should diminish, he added, and operational improvements should yield financial results.