Dear KHQD
Thanks for raising your concerns in Microsoft Community.
We understand that you want to inquire about the use of the STOCKHISTORY function. We simulated a simple call, such as the following figure:

Usually, the busy prompt is related to the network connection, Excel version or settings, and the requested exchange.
Because you need to select an exchange to use stock data, the data corresponding to different exchanges will fluctuate, so this situation may occur and cause it to fail to load. Usually, the data will appear after a while after the busy appears. If it is displayed as busy for a long time, you can try to change the exchange.
STOCKHISTORY function - Microsoft Support
You can also try the following steps:
Disable Excel's hardware graphics acceleration(You need to close all Office components first):
- Press Windows key + R, enter regedit to open the registry editor:
- Find the following path:
HKEY_CURRENT_USER\SOFTWARE\Microsoft\Office\16.0\Common\Graphics
(If there is no Graphics, please create this item manually)
- Select Graphics, right-click "New DWORD (32-bit)", name it DisableHardwareAcceleration. Double-click to open this key value and set the value to 1.
- Reopen the Office component to confirm the situation.
Disclaimer: Generally, modifying registry subkeys or work group is intended for advanced users, administrators, and IT Professionals. It can help fix some problems, however, serious problems might occur if you modify the registry incorrectly. Therefore, make sure that you follow these steps carefully. For further protection, back up the registry before you modify it. Then, you can restore the registry if a problem occurs. For more information about how to back up and restore the registry, clickHow to back up and restore the registry in Windows - Microsoft Supportto view the article.
Change network settings:
- Change your computer's network connection, which can be switched to mobile hotspot.
- Click Windows+R and type ncpa.cpl.
- Click on the name of the network you are now connected to, open the Network Status window, click Properties, in the Network Properties window, double-click on Internet Protocol version 4 (TCP/IPv4), change the Auto-DNS to "4.2.2.1" and "4.2.2.2", and then click "OK".
- Tap Windows+R and type inetcpl.cpl to open Internet Options.
- Click "Connections" in the upper menu bar, click "LAN Settings", tick "Auto-detect settings", and make sure the remaining two are unchecked, click "OK".
- Click "Advanced" on the right side of the upper menu bar, pull down the slider, tick "Restore Advanced Settings", click "Apply" on the bottom right corner, and then click "OK".
You can try the above steps and then check the operation of Excel.
In addition, regarding the Let and reduce functions you mentioned, this is also possible, but it may cause performance problems due to multiple calls to the STOCKHISTORY function in the formula. Because your STOCKHISTORY formula is a direct usage, if the amount of data is not large, we would recommend that you use it. But if the range of the table is large, it may affect performance.
STOCKHISTORY is indeed volatile, because it is a dynamic array function, it will be automatically updated according to the update of network data. It updates data based on changes in the stock market, usually instantly.
If you prefer to have data updated less frequently, you can set the data update of the STOCKHISTORY function to manual. Although Excel itself does not directly support full manual updates, you can use the following methods to reduce the frequency of updates:
Turn off automatic calculation: Go to the Formulas tab, select Calculation options, and set it to Manual. This way, Excel will not automatically recalculate all formulas every time a change is made.
I hope the above information is helpful to you. If you need further assistance, please feel free to reply.
Best Regards,
Tracy - MSFT | Microsoft Community Support Specialist