That depends on several things. Here is what could happen.
1. If the 2 HSBC accounts were the older of your accounts and the other 2 are fairly new, your score might drop since the average age of the accounts could go down.
2. Your score could also go up if say each card had a 500 limit and your had 75 on on card and the other was 0, since your total util on your card in now 7.5 % of $1000 rather then 15% even though your toal util will reamin the same. However you can do this by just paying the balance down.
3. You could get a hit for a hard INQ on your CR if HSBC deos it. I dont know if they would or not. That might also decide to change your APR and or CL.
4. Your score could remain the same.
I dont see any long term advantage to merging accounts.
1/25/2021: FICO 850 EQ 848 TU 847 EX