(new: share price performance, closing prices, tenth place in the list of major Dax daily losers)

FRANKFURT (dpa-AFX) - Black Friday for the shareholders of Siemens Energy: After withdrawn forecasts, the shares of the energy technology group plummeted before the weekend. The papers had already plunged 35.8 percent at the start of trading. In the morning, they were able to briefly reduce the minus to 26.7 percent before they were sucked back into the downward spiral.

In the end, Siemens Energy shares were down 37.3 percent at 14.65 euros. They were thus by far the worst performer in the Dax. The value of the stock fell by 7 billion euros to 12 billion euros. The shares thus joined the list of the biggest daily losers in the leading German index - in tenth place.

Shares in major shareholder Siemens also came under pressure in the wake of Energy, falling 2.2 percent. The Dax lost one percent.

Wind turbine manufacturer Siemens Gamesa remains the problem child of the Dax group. There have been significantly increased failure rates in wind turbine components, Siemens Energy said. A technical review suggests that fixing the problems with certain onshore platforms will cost significantly more than previously thought, it added. Siemens Energy currently expects additional costs to exceed one billion euros. In January, the cost had been put at 472 million euros.

This is very bad news, said one trader. If there was no indication of where the costs were going, how was the market supposed to assess it, the trader worried. He spoke of "total uncertainty."

The new problems at subsidiary Gamesa put a dark cloud in front of the group's revaluation story, wrote analyst Ajay Patel of U.S. bank Goldman Sachs. He rated the news "clearly negative". Not calculable are currently the financial consequences of the quality problems at Gamesa, wrote Nicholas Green of the U.S. analyst firm Bernstein Research.

Until the previous day, the papers had still been among the bigger winners in the Dax since the beginning of the year. They had started the rally in mid-October and in the period until the end of May posted a peak growth of 140 percent. Now, however, they also fell below the support area of the 61.8 percent Fibonacci retracement. This means that they have lost more than 61.8 percent of their gain since October - in charting terms, this is considered a massive warning signal for the entire trend. Since the beginning of the year, the papers are down almost 17 percent at a stroke, putting them at the back of the Dax field.

The wind power subsidiary Gamesa is a well-known problem for Siemens Energy, explained the capital market expert Jürgen Molnar of the trading house Robomarkets. However, after the complete takeover at the beginning of the year, Gamesa has so far proved to be a black hole in the balance sheet. "Siemens Energy's future depends more and more on whether it can get a grip on this problem child." The bitter part of the current sell-off in Energy shares is that it brings the strong recovery since last October to an abrupt end, the expert said.

Bernstein analyst Green advises investors not to take advantage of the low price of Siemens Energy to enter the market. In the worst case, namely if more than 30 percent of Gamesa's installed turbines are faulty, there is a risk of an even sharper slide in the share price. If Gamesa were valued at zero, the fair value of Siemens Energy would be eleven euros, Green calculated.

Market observer Alexander Paulus of Stock3 sees the next important supports in the price chart at 14.37 euros and 13.36 euros. Until then, the papers still have some room. In general, however, he advises after such price collapses to let the shares "settle out first" and to wait for a first attempt to form a bottom. Chart supports rarely have an effect in the midst of a selling panic./ajx/tih/ag/jha/la/stk