** Shares in Allegro ALEP.WA are down around 5% to their lowest since mid-April after the e-commerce company trimmed its volume growth guidance
** Allegro sees its GMV rising between 9% and 9.5% in Poland this year, vs an earlier guidance for around 10% growth
** J.P.Morgan analysts describe Allegro's third-quarter results as "solid," but say they see downgrade as "an incremental negative"
** Stock is at the bottom of Polish blue-chip .WIG20 index, which is up around 0.6%
(Reporting by Anna Pruchnicka)
((anna.pruchnicka@tr.com))