LONDON (Reuters) - German financial watchdog Bafin said on Friday that it has started an assessment probe into the trading of Steinhoff (>> Steinhoff International Holdings) shares this week, after the stock lost more than 80 percent of its value within days.

Bafin routinely investigates incidents every year to uncover market manipulation and insider trading. Usually, such analyses are triggered by suspicious transaction reports or by exceptionally high trading volumes.

Steinhoff's shares fell by another 40 percent on Friday before paring losses by late morning, after Moody's cut its credit rating and raised concerns about the company's governance, deepening the South African retailer's problems, whose primary listing is in Frankfurt.

(Reporting by Tom Bergin; Writing by Arno Schuetze; Editing by Victoria Bryan)