The Nikkei stock average hit a new all-time high.
This stock reached a year-to-date high today.
高値 simply means 'high price' or 'high level', not necessarily a record. 最高値 specifically means the highest price ever.
all-time low; record low; new low · lowest price
Compound of 最高 (さいこう, 'highest') + 値 (ね, 'price'). The reading さいたかね is a standard compound reading.