  Persisting tensions between high-redshift and low-redshift cosmological
observations suggest the dark energy sector of the Universe might be more
complex than the positive cosmological constant of the $\Lambda$CDM model.
Motivated by string theory, wherein symmetry considerations make consistent AdS
backgrounds (\textit (i.e.) maximally symmetric spacetimes with a negative
cosmological constant) ubiquitous, we explore a scenario where the dark energy
sector consists of two components: a negative cosmological constant, with a
dark energy component with equation of state $w_{\phi}$ on top. We test the
consistency of the model against low-redshift Baryon Acoustic Oscillation and
Type Ia Supernovae distance measurements, assessing two alternative choices of
distance anchors: the sound horizon at baryon drag determined by the
\textit{Planck} collaboration, and the Hubble constant determined by the SH0ES
program. We find no evidence for a negative cosmological constant, and mild
indications for an effective phantom dark energy component on top. A model
comparison analysis reveals the $\Lambda$CDM model is favoured over our
negative cosmological constant model. While our results are inconclusive,
should low-redshift tensions persist with future data, it would be worth
reconsidering and further refining our toy negative cosmological constant model
by considering realistic string constructions.
