Pfizer Inc’s (PFE.N) buyout bid for Allergan Plc (AGN.N) has financial markets on edge over a possible new move by the U.S. Treasury Department against tax-inversion deals, but the outlook for any such steps was still unclear on Friday. For months, Treasury has offered no fresh guidance on the inversion issue, leaving tax experts to speculate about what could come next. Inversions typically involve a U.S. multinational buying a smaller foreign rival and relocating to its home country, if only on paper, to escape U.S. taxation.