Movement to a Piano Concerto in C (draft to K. 503) (K. 502a)

What Is Known

K. 502a is an authentic, extant fragment: an uncompleted concerto movement in C major for clavier and orchestra, preserved in Mozart’s autograph as one leaf (two written pages) without an original title [1]. The Köchel Verzeichnis dates the piece to Vienna, 1784–1785 (rather than 1786) [1].

The scoring listed in the Mozarteum catalogue matches Mozart’s late-Viennese “grand C-major” palette—solo keyboard with flute, pairs of oboes and bassoons, horns, trumpets, timpani, and strings—suggesting a public-concerto ambition akin to K. 503 [1]. The fragment has been transmitted in later copies under headings such as “beginning of a clavier concerto,” reinforcing that what survives is essentially an opening span rather than a complete, performable movement [1].

Musical Content

What survives appears to be the start of a first movement: music that sets up the concerto’s initial argument (likely in sonata-allegro terms), but breaks off before Mozart can carry it through the large-scale piano–orchestra dialogue typical of his mature Viennese concertos. In this period Mozart was writing on a symphonic scale for the keyboard concerto, and K. 503—completed on 4 December 1786—stands as the fully realized C-major summit toward which this abandoned draft points [2]).