Allegro in C minor for Two Pianos (fragment), K. 426a
von Wolfgang Amadeus Mozart

Mozart’s Allegro in C minor for two pianos (fragment), K. 426a, survives as a single-page torso from Vienna (likely December 1783), offering a brief glimpse of his serious, contrapuntal-leaning keyboard manner at age 27.[1]
What Is Known
Only a short, incomplete Allegro for two keyboards (two pianos) survives, notated on a single page and transmitted as a fragment in the Neue Mozart-Ausgabe appendix (K. 426a / Anh. 44).[2] The surviving page itself bears the heading Allegro and indicates Vienna and December 1783, consistent with Mozart’s intense engagement that year with C-minor counterpoint and keyboard ensemble writing.[3] Beyond that, documentation is slight: there is no known complete continuation, and the intended overall scale and destination (standalone duet movement or part of a larger design) remain uncertain.
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Musical Content
What survives begins decisively in C minor (alla breve), with both parts set in a compact, two-piano texture rather than a solo-with-accompaniment layout.[3] Piano I states a firm opening idea marked f, followed by tightly worked, sequential figuration; Piano II answers with close-position harmonies and a steady, grounded underpinning. A contrasting, quieter passage (p) follows, thinning the texture and shifting the register upward before the fragment breaks off mid-thought—suggesting an exposition-like beginning without reaching a cadence that would clarify the movement’s larger form.[3]
[1] IMSLP work page with cataloguing, scoring, and publication/scan links for K. 426a (fragment).
[2] Digital Mozart Edition (Neue Mozart-Ausgabe) PDF contents page showing the fragment listed as “Allegro in C minor for two Keyboards (fragment) KV App. 44 (426a)”.
[3] IMSLP preview image (NMA scan) of the surviving page of the *Allegro* fragment, showing heading, key, meter, dynamics, and the extent of the surviving music.




