  The classical Maclaurin inequality asserts that the elementary symmetric
means $$ s_k(y) = \frac{1}{\binom{n}{k}} \sum_{1 \leq i_1 < \dots < i_k \leq n}
y_{i_1} \dots y_{i_k}$$ obey the inequality $s_\ell(y)^{1/\ell} \leq
s_k(y)^{1/k}$ whenever $1 \leq k \leq \ell \leq n$ and $y = (y_1,\dots,y_n)$
consists of non-negative reals. We establish a variant $$
|s_\ell(y)|^{\frac{1}{\ell}} \ll \frac{\ell^{1/2}}{k^{1/2}} \max
(|s_k(y)|^{\frac{1}{k}}, |s_{k+1}(y)|^{\frac{1}{k+1}})$$ of this inequality in
which the $y_i$ are permitted to be negative. In this regime the inequality is
sharp up to constants. Such an inequality was previously known without the
$k^{1/2}$ factor in the denominator.
