  We present the observations and analysis of a high-magnification microlensing
planetary event, KMT-2022-BLG-0440, for which the weak and short-lived
planetary signal was covered by both the KMTNet survey and follow-up
observations. The binary-lens models with a central caustic provide the best
fits, with a planet/host mass ratio, $q = 0.75$--$1.00 \times 10^{-4}$ at
$1\sigma$. The binary-lens models with a resonant caustic and a brown-dwarf
mass ratio are both excluded by $\Delta\chi^2 > 70$. The binary-source model
can fit the anomaly well but is rejected by the ``color argument'' on the
second source. From Bayesian analyses, it is estimated that the host star is
likely a K or M dwarf located in the Galactic disk, the planet probably has a
Neptune-mass, and the projected planet-host separation is $1.9^{+0.6}_{-0.7}$
or $4.6^{+1.4}_{-1.7}$ au, subject to the close/wide degeneracy. This is the
third $q < 10^{-4}$ planet from a high-magnification planetary signal ($A
\gtrsim 65$). Together with another such planet, KMT-2021-BLG-0171Lb, the
ongoing follow-up program for the KMTNet high-magnification events has
demonstrated its ability in detecting high-magnification planetary signals for
$q < 10^{-4}$ planets, which are challenging for the current microlensing
surveys.
