*Nikkei down 1.5 pct in a broad sell-off after Monday's rally
*Investors lock in profits amid uncertainty
*Shippers decline sharply after key index extends losses (Adds stocks and comments)
By Taiga Uranaka
TOKYO, Sept 9 (Reuters) - The Nikkei average fell 1.5 percent on Tuesday, as investors booked profits after a sharp rally the previous day on the U.S. government's bailout of top mortgage firms, and amid continued uncertainty over the health of the global economy.
Japan's top banks fell back from double-digit percentage gains seen on Monday, and shippers such as Kawasaki Kisen Kaisha Ltd <9107.T> declined sharply after a key freight index fell to its lowest point in more than a year.
Hitachi Construction Machinery <6305.T> and ferronickel producer Pacific Metals <5541.T> jumped after they were chosen to join the benchmark index in a regular reshuffle.
Market participants said investors still have much to worry about, including earnings from U.S. investment banks, such as Lehman Brothers <LEH.N>.
"Today is the day after the party," Fujio Ando, senior managing director at Chibagin Asset Management.
"In hindsight, yesterday's rally was merely caused by the buying back of oversold shares."
The benchmark Nikkei <
> ended the morning down 185.43 points at 12,439.03. The index had jumped 3.4 percent on MondayThe broader Topix <
> lost 1.8 percent to 1,194.97."The U.S. rescue plan has prevented a worst-case scenario but when you give it some thought, the situation has not changed. It does not help improve U.S. employment figures, for instance," said Fumiyuki Nakanishi, manager of investment information at SMBC Friend Securities.
The Nikkei failed to end above a key technical ceiling around 12,620 on Monday, suggesting to chart watchers that the market lacked momentum to sustain gains, he said.
BANKS SLIP
Top lender Mitsubishi UFJ Financial Group <8306.T> declined 2.8 percent to 826 yen, and No.2 Mizuho Financial Group <8411.T> slid 3 percent to 449,000 yen. Both had risen by their daily limits on Monday.
Shipper Kawasaki Kisen Kaisha Ltd <9107.T> lost 6.1 percent to 657 yen and rival Mitsui OSK fell 5.1 percent to 1,100 yen.
A key freight index <.BADI> fell 3 percent to hit its lowest since late June 2007, pointing a fall in sea cargo traffic, another indicator of a slowing global economy.
Exporters also faced a broad sell-off, with Honda Motor Co Ltd <7267.T> falling 3 percent to 3,540 yen, becoming the biggest drag on the Nikkei.
Hitachi Construction Machinery rose 4.3 percent to 2,425 yen and ferronickel producer Pacific Metals jumped 3.2 percent to 675 yen after the publisher of Japan's benchmark stock average said the two firms would join the Nikkei 225 average <
> in a reshuffle. [ ]The Nikkei Inc also said it would remove builder Kumagai Gumi <1861.T> and chemical maker Toagosei <4045.T> in the reshuffle on Oct. 1 due to a decline in liquidity in those stocks. Kumagai Gumi was down 5.5 percent at 52 yen and Toagosei tumbled 10.8 percent to 357 yen.
Trade slowed on the Tokyo exchange's first section, with 798 million shares changing hands, compared with last week's morning average of 859 million.
Declining stocks outpaced advancing ones by more than 3 to 1. (Editing by Edwina Gibbs)