Sowell Financial Services Expands Stake in Allison Transmission Sowell Financial Services recently acquired 19,731 shares of Allison Transmission Holdings, Inc., signaling confidence in the company's valuation. Allison's stock performance has been resilient, with a one-year range of $71.49 to $122.53. The auto parts firm continues to attract investor interest, supported by strong earnings and an active share buyback program.1