Clearly you have no idea about anything, Retail trading and investment has seen a HUGE increase since the start of the pandemic. As have most internet based services obviously. IG and every other broker have had months to improve their back end and improve capacity. Its not a question of that. The issue here is broader, It's quiet obvious that under extremely volatile conditions they're going to restrict margins etc. It's common practice. The problem here is that they're restricting CASH ACCOUNTS, Not only are they restricting cash accounts but they're allowing you to close positions and not buy. If this is as you say a matter of clearing, They have had all weekend to allocate resources/extra hardware for the expected traffic. If this was still an issue they would just suspend the ticker and not allow you to close.