In September, 2018 we introduced several new functions in a family of functions called dynamic arrays. These functions will automatically populate a range, or array, and eliminate the need for legacy Ctrl+Shift+Enter (CSE) array formulas. Dynamic arrays do have performance implications with regards to how they manage implicit intersection, which are often used in financial summaries.
In dynamic aware Excel, Excel will not attempt to do implicit intersection. Rather, it will interpret the formula as an array formula.
Implicit intersection was used by non-dynamic array aware Excel to prevent a formula from returning an array. However, now that the grid natively understands arrays, there is no need to silently perform implicit intersection.
If you would like a formula to perform implicit intersection in dynamic array aware Excel, you can make use of the Implicit Intersection Operator (@).
If a formula authored in non-dynamic aware Excel relied on implicit intersection, that formula will be preceded by @ when opened in dynamic array Excel. The @ will be removed on save to facilitate compatibility with non-dynamic aware Excel.