How do root position and inversions change the stability of a triad?

In the context of Western harmony, the stability of a triad is determined by its arrangement of notes, specifically which note serves as the bass.

A triad in root position—where the root note is in the lowest position—is considered the most stable arrangement. It provides a sense of finality and repose, which is why it is frequently used at the end of a musical composition.1

In contrast, inversions occur when the third or fifth of the chord is placed in the bass. Theorists have observed that these inverted chords are inherently less stable than those in root position. Because they lack the same degree of finality, they do not function as effectively as a concluding chord. This instability is a fundamental aspect of harmonic movement; by utilizing different inversions, composers create a sense of tension and relaxation, driving the musical flow forward toward a more stable resolution.12