Stock Market Stem Mixer presents a design for patching, mapping and scaling global stock market data feeds to alter tracks produced in the stem.mp4 remix format (introduced in 2015). It provides a mechanism for listeners to engage in varied creative interaction with audio content, without a burdensome learning curve. The system parses and stores 16 days of end-of-trading share values for four global IT/entertainment conglomerates. Using this data, each company is assigned four banks of parameters that can be used to dynamically shape the four stem file parts. A roulette-style betting format is exploited to provide an intuitive user interface, to represent the chance aspect of resulting sonic manipulations and to comment playfully on the free market forces that now mediate audio cultural life via digital distribution channels.