The critical exponent
E
(
u
)
E(\mathbf u)
of an infinite sequence
u
\mathbf u
over a finite alphabet expresses the maximal repetition of a factor in
u
\mathbf u
. By the famous Dejean’s theorem,
E
(
u
)
≥
1
+
1
d
−
1
E(\mathbf u) \geq 1+\frac 1{d-1}
for every
d
d
-ary sequence
u
\mathbf u
. We define the asymptotic critical exponent
E
∗
(
u
)
E^*(\mathbf u)
as the upper limit of the maximal repetition of factors of length
n
n
. We show that for any
d
>
1
d>1
there exists a
d
d
-ary sequence
u
\mathbf u
having
E
∗
(
u
)
E^*(\mathbf u)
arbitrarily close to
1
1
. Then we focus on the class of
d
d
-ary balanced sequences. In this class, the values
E
∗
(
u
)
E^*(\mathbf u)
are bounded from below by a threshold strictly bigger than 1. We provide a method which enables us to find a
d
d
-ary balanced sequence with the least asymptotic critical exponent for
2
≤
d
≤
10
2\leq d\leq 10
.