## 6 Conclusions  
Given that the BBTS is frequently used to predict the movement of spot prices as well as the trend of spot price movements for these two cryptocurrencies (Bitcoin and ETH), we investigate whether investors can profit by trading these two cryptocurrency spots based on the BBTS (i.e., buying these two spots as these two spot prices penetrating the lower Bollinger Bands and after selling these two spots as penetrating the upper Bollinger Bands). The results show that investors can search for a significant average holding return (AHR) in the heatmap matrix using our new design. Moreover, using our new design would result in higher AHRs in the red area, all of which are higher than the highest return in blue derived from the conventional design in this study. Given that the majority of the AHRs in both heatmap matrices are positive, it implies that contrarian trading strategies are appropriate for trading these two cryptocurrency spots following the BBTS. Thus, this study can contribute to the existing literature in several ways. First, we investigate whether investors would profit from trading either Bitcoin spot or ETH spot, two of the most popular cryptocurrency spots, using the BBTS, one of the most popular trading strategies in trading spot and futures (e.g., index, commodity, and cryptocurrency spots and futures), which are rarely addressed in the existing literature. Second, given that rebounding cryptocurrency spot prices may occur after spot price overreaction following the BBTS, we argue that owing to the relatively high volatilities of cryptocurrency spot prices, investors trading these two cryptocurrency spots may induce even higher spot prices rebounded from oversold signals to overbought signals emitted by BBTS, thus likely generating even higher profits compared to trading stocks using the BBTS, which may result from the higher volatiles of cryptocurrency spot prices. Third, using our new design would generate higher returns in some areas in red that are all higher than the highest return in blue derived from the conventional design in this study. We believe that our impressive findings are the result of big data analytics and the flexibility of BBTS, both of which are taken into account by our new design. Fourth, our new design will be considered by some investors because, if history repeats itself, our findings may inspire investors to trade cryptocurrency spots owing to the positive and impressive results obtained by implementing the new design proposed in this study. Furthermore, we contend that the findings of this study may have the following valuable implications for market participants: first, by using the BBTS, investors can profit (as shown by positive AHPs in Table 2), even significantly (as shown by red cells in Tables 3 and 4), from trading cryptocurrency spot, implying that the BBTS may be appropriate for investors trading cryptocurrency spot. Second, by using historical data, investors may obtain various profitable outcomes by employing the BBTS with different SDs and different-day MAs, implying that investors can analyze these potential outcomes with big data analytics in advance, which may be beneficial to market participants in exploiting higher profits following the BBTS. Third, this study can provide valuable information for increasing profitability when trading cryptocurrency spots because proper preparation is required for increasing profitability and even lowering risks when trading such contracts. Third, this study can provide valuable information for increasing profitability when trading cryptocurrency spot contracts because proper preparation is required for increasing profitability and even lowering risks when trading these cryptocurrencies. This paper describes a study on the Bollinger Bands trading strategy (BBTS) as applied to Bitcoin and Ethereum spots. Regardless of the study's potential contributions, some limitations can exist.