Alstom shares plunged by a fifth at one point on Wednesday after the train maker said it would sell assets, cut jobs and consider a capital raise after a cash flow warning in October increased concerns about the company’s debt level.

The manufacturer of France’s high-speed TGV locomotives said it hoped a divestment program would raise €1 billion ($1.09 billion), while costs would be reduced through the trimming of about 1,500 positions as it looked to bolster its balance sheet. Alstom said it is targeting a reduction in its…