Price return (or 'price effect') is the uncertain, speculative component of horizon return: it's the gain or loss from yield/spread changes you don't control. If yields fall 50bp, price return is positive (you win); if yields rise 50bp, price return is negative (you lose). This is separate from roll-down (which assumes no yield change). Critically: carry and roll-down are somewhat predictable (you earn them if markets don't move much), but price return is pure speculation — you're betting on rate direction. Many traders focus on maximizing carry + roll-down while minimizing exposure to adverse price moves (negative convexity, duration mismatches). Horizon analysis helps you see which part of your expected return is 'locked in' versus dependent on your yield view being correct.