MSTMCT-This paper presents an optimal algorithm for solving the problem of simultaneous fanout optimkation and routing tree construction for an ordered set of critical sinks. The algorithm, which is based on dynamic programming, generates arectilinear Steiner tree routing solution containing appropriately shed and placed buffers. The resulting solution,} vhich inherits the topology of LT-Trees and the detailed structure of P-Trees, maximhes the signal required time at the driver of the given set of sinks. Experimental results on benchmark circuits demonstrate the effectiveness of this simultaneous approach compared to the sequential methods.