* Huge sell-off translates into falling confidence in 'Abenomics'-traders
* Foreigners likely sold even more this week - traders
* Nikkei trades below its book value, fell 11 pct this week alone
By Ayai Tomisawa
TOKYO, Feb 12 (Reuters) - Net selling of Japanese cash stocks by foreign investors hit a near five-month high in the week of Feb. 1-5, exchange data showed, as a stronger yen and worries about a global economic slowdown threatened to erode exporters' profits.
Foreigners sold 611.25 billion yen ($5.5 billion) of Japanese cash stocks on a net basis during the week, the largest amount since mid-September, according to data released by the Japan Exchange Group on Friday.
Japanese stocks briefly rose and the yen fell after the Bank Of Japan's unexpected decision to adopt negative interest rates on Jan. 29, but they quickly reversed direction as investors dumped riskier assets and looked for safe havens as global market turmoil dragged on.
"Current market levels are a reflection of investors' fears about intensified selling in crude oil this year and worries that a strong yen could eat into exporters' earnings," said Takuya Takahashi, a strategist at Daiwa Securities.
"Moreover, the huge sell-off translates into falling confidence in 'Abenomics'."
Traders said foreign investors likely dumped even more Japanese shares this week.
The Nikkei share average tumbled 11.1 percent this week, the biggest weekly drop since October 2008, hit by a sharp rise in the yen and concerns about stress in the global banking system.
Japanese markets were closed for a public holiday on Thursday, when the dollar fell as low as 110.985 yen.
As of Friday, the Nikkei share average was trading below its book value, while nearly 60 percent of the names on the Tokyo Stock Exchange's first section were trading below their book value, compared to 44 percent at end-December, according to brokerage data.
On the other hand, trust banks, which manage corporate pension trusts and national pension fund trusts, bought a net 25 billion yen in Japanese cash stocks. They were net buyers of Japanese cash stocks for the 11th consecutive week. ($1 = 111.9600 yen) (Editing by Kim Coghill)