<p>This paper examines a combination of HAR and neural networks
methods to better predict perceived volatility and, consequently, to more
efficiently manage risk. To carry out the projections, combinations and
tests, the series of perceived volatility of Ibovespa was collected between
2000 and 2018, producing a sample of 4,530 observations. The main results
show that the combination of both models better predict perceived
volatility, which can be interpreted as an efficiency gain for risk
management. In addition, this article also evaluates the performance of the
models, considering the profitability of trading with options. For the case
of profitability, combinations of linear and nonlinear models present better
performance.</p>