  A plasma scenario with negative triangularity (NT) shaping is achieved on
MAST-U for the first time. While edge localized modes (ELMs) are eventually
suppressed as the triangularity is decreased below $\delta$ < -0.06, an
extended period of H-mode operation with Type-III ELMs is sustained at less
negative $\delta$ even through access to the second stability region for ideal
ballooning modes is closed. This documents a qualitative difference from the
ELM-free access conditions documented in NT scenarios on conventional aspect
ratio machines. The electron temperature at the pedestal top drops across the
transition to ELM-free operation, but a steady rise in core temperature as
$\delta$ is decreased allows for similar normalized beta in the ELM-free NT and
H-mode positive triangularity shapes.
