China stocks rout on first market day of 2016 trips national trading halt
* Chinese major CSI300 index tumbles 7 pct
* After market slump, "circuit breaker" halts trade
* Worst trading day since stock market crash in Aug 2015
* Investors react to weak data, end of share lockup period
* Circuit-breaker seen by some as emboldening market bears
* U.S.-listed ETF hints at more selling on Tuesday (Updates with U.S. midday activity in paragraphs 3, 4 and 10)
By Pete Sweeney and Samuel Shen
SHANGHAI, Jan 4 (Reuters) - China's major stock exchanges tanked on the first trading day of the year, triggering a "circuit-breaker" that suspended equities trade nationwide for the first time and putting at risk months of regulatory work to restore market stability.
The selloff saw the CSI300 index of the largest listed companies in Shanghai and Shenzhen lose 7.0 percent before trading was suspended, its worst single-day performance since late August 2015, the depth of a summer stock market rout. Continuación...