The Swiss competition regulator has opened an investigation into possible collusion in the precious metals market by several major banks, it said on Monday, the latest in a string of manipulation probes. Switzerland’s WEKO watchdog said its investigation, the result of a preliminary probe, was looking at whether UBS (UBSG.VX), Julius Baer (BAER.VX), Deutsche Bank (DBKGn.DE), HSBC (HSBA.L), Barclays (BARC.L), Morgan Stanley (MS.N) and Mitsui conspired to set bid/ask spreads.