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We report the 488 and 514 nm anion photoelectron spectra of NbMo$\mathrm{<mrow\; data-mjx-texclass="ORD">-</mrow>}$. R2PI spectroscopic studies have established that neutral NbMo has a $\mathrm{<mrow\; data-mjx-texclass="ORD">2</mrow>}\Delta 5/2$ ground state and a short bond length . We find that the NbMo$\mathrm{<mrow\; data-mjx-texclass="ORD">-</mrow>}$ anion has a $\mathrm{<mrow\; data-mjx-texclass="ORD">1</mrow>}\Sigma +$ ground state in which the "extra" electron occupies the (4d)$\delta$ bonding orbital, giving a $1\sigma 21\pi 41\delta 42\sigma 2$ valence electron configuration. Thus, NbMo$\mathrm{<mrow\; data-mjx-texclass="ORD">-</mrow>}$ has a formal bond order of 6, and is isoelectronic with Mo$2$. Low-lying excited states of NbMo ($\mathrm{<mrow\; data-mjx-texclass="ORD">2</mrow>}\Sigma +$) and NbMo$\mathrm{<mrow\; data-mjx-texclass="ORD">-</mrow>}$ ($\mathrm{<mrow\; data-mjx-texclass="ORD">3</mrow>}\Delta$) are also observed. The spectra provide the electron affinity of NbMo, energies of the $\mathrm{<mrow\; data-mjx-texclass="ORD">2</mrow>}\Sigma +$ and $\mathrm{<mrow\; data-mjx-texclass="ORD">3</mrow>}\Delta$ excited states, vibrational frequencies in the anion and neutral molecule ground states and the $\mathrm{<mrow\; data-mjx-texclass="ORD">2</mrow>}\Sigma +$ state, $\mathrm{<mrow\; data-mjx-texclass="ORD">2</mrow>}\Delta$ and $\mathrm{<mrow\; data-mjx-texclass="ORD">3</mrow>}\Delta$ spin-orbit splittings, and (from Franck-Condon analyses) bond length measurements for the anion ground state and the observed excited states. These results are compared with previous anion photoelectron spectroscopic data for the Group 5/6 congeners VCr and VMo, and with density functional theory predictions.