We demonstrate using symmetry adapted cluster theory with configuration$\backslash$ninteraction \(SAC-CI)\ that charging of small \PbSe\ nanocrystals$\backslash$n\(NCs)greatly modifies their electronic states and optical excitations.$\backslash$nConduction and valence band transitions that are not available in$\backslash$nneutral \NCs\ dominate low energy electronic excitations and show$\backslash$nweak optical activity. At higher energies these transitions mix with$\backslash$nboth single excitons \(SEs)\ and multiple excitons \(MEs)\ associated$\backslash$nwith transitions across the band-gap. As a result, both \SEs\ and$\backslash$n\MEs\ are significantly blue-shifted, and \MEgeneration is drastically$\backslash$nhampered. The overall contribution of \MEs\ to the electronic excitations$\backslash$nof the charged \NCs\ is small even at very high energies. The calculations$\backslash$nsupport the recent view that the observed strong dependence of the$\backslash$n\ME\ yields on the experimental conditions is likely due to the effects$\backslash$nof \NC\ charging.