Figure 12: NFLX prediction (Picture credit: Original).
As shown in Figure 12, the SHAP analysis results
of NFLX also show that the price of the previous day
(Price_t-1) is the most important, followed by the last
3 days (Price_t-3) and the previous 5 days (Price_t-
5). This is like the situation of DPZ, indicating that
NFLX predictions strongly rely on historical price
information from recent and past days.
In summary, the feature importance analysis of
the four assets shows that the MLP model generally
relies heavily on the most recent one-day price
information (Price_t-1) when predicting future prices
and then selectively refers to other lagged days of
prices based on the characteristics of different assets.
This reflects that the model can capture the price
volatility characteristics of different assets.
4 CONCLUSIONS
In the experiments, all models achieved high
accuracy on the stock assets (AMZN, DPZ, NFLX),
with R² values around 0.96–0.97. The simpler Linear
Regression baseline performed nearly as well as the
neural models on these well-behaved series.
However, the neural models outperformed for the
volatile cryptocurrency: the MLP and CNN achieved
the highest R² (≈0.92–0.93) while Linear Regression
and the GNN were lower (≈0.86–0.88). This indicates
that the nonlinear learning capacity of the MLP and
CNN helps capture Bitcoin’s erratic behavior better
than the linear model or the GNN.
SHAP analysis revealed that, for each model, the
most recent price lags were the dominant features
influencing predictions. This confirms that all models
rely primarily on immediate price history in one-step
forecasting. Overall, deeper models provided only
marginal gains on stable stock forecasts but delivered
more benefit on the highly volatile asset.
This study has limitations. We used only historical
adjusted closing prices as inputs to predict next day
closing prices, without incorporating additional
potentially influential variables such as
macroeconomic factors, or market sentiment data.
Including these additional features could enhance
predictive performance. Furthermore, the graph
construction for the GNN was relatively
straightforward, utilizing only temporal relationships
within individual assets; constructing more complex,
multi-asset interaction graphs might further improve
forecasting accuracy. Additionally, this research
focused exclusively on one-step-ahead predictions
evaluated via the R² metric; future studies could
extend analyses to multi-day forecasts, employ
alternative evaluation metrics, and explore more
sophisticated neural network architectures. Despite
these limitations, the study provides a comprehensive
comparison among predictive models and highlights
the importance of interpretability in financial time
series forecasting.
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