* For the week, Nikkei has risen 1.3 pct
* Toshiba dives after confirming Westinghouse's losses
* Shipping, metal, trading house stocks underperform
By Ayai Tomisawa
TOKYO, Nov 13 (Reuters) - Japan's Nikkei share average tumbled on Friday morning, snapping a seven-day winning streak after a sharp drop in Wall Street and as weaker commodity prices weighed on stocks such as metals companies and trading houses.
Underperforming the already weak market was Toshiba Corp , which dived more than 8 percent after it said its U.S. nuclear unit Westinghouse had booked losses in the 2012 and 2013 fiscal years. It was the fourth biggest loser on the board.
The Nikkei dropped 0.9 percent to 19,522.48 in midmorning trade after rising 5.4 percent for the past seven days. For the week, the index has risen 1.3 percent.
"The market started to get cautious on heightened expectations that the Fed will raise interest rates soon," said Nobuhiko Kuramochi, a strategist at Mizuho Securities, adding that Japanese stocks are prone to profit-taking given the recent rises.
Investors are staying cautious on whether the U.S. Federal Reserve will raise rates in December for the first time in nearly a decade, as is widely expected after recent strong jobs data.
In a speech on Thursday, Fed Chair Janet Yellen did not comment on the economy or the timing of a rate hike.
However, New York Fed President William Dudley said it was possible that the conditions the central bank had established to begin normalising monetary policy "could soon be satisfied".
All of Topix's 33 subsectors were in negative territory, with shippers, mining and nonferrous metal stocks as well as trading houses leading the losses.
Mitsui OSK Lines dropped 2.4 percent, Toho Zinc shed 2.9 percent, Sumitomo Metal Mining fell 2.5 percent, and Mitsui & Co declined 2.0 percent.
Gold fell to its lowest level since early 2010 on Thursday, Copper fell to a six-year low, while U.S. crude oil dipped further in early trading on Friday to over two-month lows.
The broader Topix dropped 0.8 percent to 1,581.69 and the JPX-Nikkei Index 400 shed 0.8 percent to 14,245.22.
Reporting by Ayai Tomisawa; Editing by Sam Holmes