Take two independent triangular arrays $x_{N,i}$ and $y_{N,i}$ for $1 \le i \le N$. Suppose that the sample means both converge in probability to zero $$ \frac1N \sum_{i=1}^N x_{N,i} \xrightarrow{\mathcal{P}} 0 $$ $$ \frac1N \sum_{i=1}^N y_{N,i} \xrightarrow{\mathcal{P}} 0 $$ and further all sample moments of every order $n \ge 2$ converge in probability to some constants $$ \frac1N \sum_{i=1}^N |x_{N,i}|^n \xrightarrow{\mathcal{P}} a_n $$ $$ \frac1N \sum_{i=1}^N |y_{N,i}|^n \xrightarrow{\mathcal{P}} b_n $$ Then is it true that the sample covariance converges in probability to zero? $$ \frac1N \sum_{i=1}^N x_{N,i}y_{N,i} \xrightarrow{\mathcal{P}} 0 $$ In the case of finite moments this is easy to show with expectation, but I am struggling to find a reference otherwise.