Italian term (edited): titoli contabilizzati in conto proprietà

Precious little context. Are they the financial statements of a banK or perhaps an asset management company a fund perhaps?
A bank or a fund may manage securities on behalf of its clients. Alternatively it may manage securities it actually owns itself, in which case these are "proprietary securities".
However often Italian banks will often talk about "titoli propri" making this point when it is unnecessary and already clearly obvious from the context (they don't manage any assets on behalf or customers) and to translate it "accurately" would only confuse a reader.