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 (Recasts first paragraph, updates prices to reflect market U.S. close, adds quote from market analyst)
By Pete Sweeney and Samuel Shen
SHANGHAI, Jan 4 (Reuters) - China's major stock exchanges looked set to extend losses after shares plunged on the first trading day of the year, triggering a "circuit breaker" that suspended equities trade nationwide for the first time and put months of regulatory reforms at risk.
The sell-off saw the CSI300 index of the largest listed companies in Shanghai and Shenzhen plunge 7.0 percent before trading was suspended, its worst single-day performance since late August, the depth of a summer stock market rout. Continuación...