Firms that invest in research and development (R&D) for growth opportunities are affected by their size, debt levels, and industry concentration. Large firms have an advantage over small firms, but this advantage disappears as their debt levels increase. Small firms with high debt levels actually benefit the most from R&D investments. These findings help explain why previous studies on the value of R&D have shown inconsistent results when considering size and debt separately. Investors also consider specific factors of each firm when valuing their R&D investments.