The deep research logic is organized as follows: 

Okay, let's tackle this question: "Why did BWB's trading volume surge?" 

First, I need to look at the references provided. The user is asking about the surge in trading volume for Bridgewater Bancshares (BWB). Let me check the references for any data related to BWB's trading volume.

Looking through the references, numbers 19 and 20 mention BWB's trading volume surge on April 15, 2025. Reference 19 shows a QoQ (quarter-over-quarter) growth value of -43,581, which might indicate a significant change in volume. Reference 20 provides more details: the trading volume on April 15 was 49,497 shares, with a growth of -46.82% compared to previous days. Wait, that seems contradictory. A negative growth percentage would mean the volume decreased, but the user is asking about a surge. Maybe there's a misunderstanding here. Let me check the data again.

Reference 19's "Trading Volume QoQ growth value" is listed as -43,581. The "growth" here might be a net change rather than a percentage. So if the previous quarter's volume was lower, a negative number could indicate a decrease. But the user is asking about a surge, so perhaps there's a different angle. Reference 20 mentions a growth of -46.82%, which is a decrease, but the absolute growth is 0.47. That's confusing. Maybe the data is misrepresented. Alternatively, perhaps the surge happened on a specific day, and the references are showing the change from the previous day or quarter.

Wait, the user is asking about the surge on April 15, 2025. Reference 19's data is for April 15, 2025, with a trading volume of 49,497 shares. The growth is -46.82%, which suggests a decrease from the previous day. But the user is asking why the volume surged. There's a contradiction here. Maybe the data in the references is incorrect, or perhaps the surge happened on a different date. Let me check other references.

Reference 6 mentions that on April 15, 2025, BWB shares surged 3.34%, reaching an intraday high of $13.08. The trading volume was 24,338 shares, which is 50.7% of the average daily volume of 47,991. Wait, that's lower than average. But the user is asking about a surge in volume. There's a discrepancy here. Maybe the surge happened on a different date. Let me check the other references.

Reference 25 is about BWB news on April 15, 2025, but it shows 0 results. Reference 23 also shows 0 results for institutional buying activity on April 15. So, the data in references 19 and 20 might be the only relevant ones. However, they indicate a decrease in volume, not a surge. This is confusing. Perhaps the surge occurred on a different date, but the user is asking about April 15. Alternatively, maybe the data in the references is misrepresented.

Wait, looking back at reference 19, the "Trading Volume QoQ growth value" is -43,581. If the previous quarter's volume was lower, a negative number could mean a decrease. But if the current quarter's volume is higher, the negative might be a mistake. Alternatively, maybe the data is presented as a net change, not a percentage. For example, if the previous quarter had 10,000 shares and the current quarter has 56,419 (10,000 + 46,419), the growth would be positive. But the data here is -43,581, which doesn't align. This is unclear.

Alternatively, perhaps the surge in volume is due to news related to BWB. Let me check the other references for any news around April 15. Reference 3 mentions that BWB is scheduled to announce Q1 2025 results on April 23, 2025. That's after April 15. Reference 4 is about Q4 2024 results announced on January 29, 2025. Reference 5 is general news about BWB. Reference 6 is about the stock surge on April 15, but the volume was lower than average. Reference 7 is about valuation metrics. Reference 8-12 discuss market volatility and tariffs, which might have affected the broader market but not specifically BWB. Reference 13 is about water repairs in Bridgewater, NJ, unrelated to the stock. Reference 14-18 discuss Bank of America and Fed policies. Reference 19-20 are the volume data. Reference 21-22 discuss Fed policies and Bank of America. Reference 23-25 are about BWB news but show 0 results. Reference 26-33 are about Apple (AAPL), not relevant here.

So, the only relevant data points are references 19 and 20, which indicate a decrease in volume on April 15. However, the user is asking about a surge. This is conflicting. Maybe there's a misunderstanding in the data presentation. Alternatively, perhaps the surge happened on a different date, but the user is asking about April 15. 

Wait, reference 6 mentions that on April 15, BWB surged 3.34%, but the volume was 24,338 shares, which is 50.7% of the average. That's lower than average, not a surge. So, the volume didn't surge on that day. Therefore, the answer might be that there was no surge in volume on April 15, but perhaps the user is referring to a different date. However, the user's question is about the surge, so I need