There is a narrowness to the US stock market’s “strength” so far in 2023 that warrants attention. Out of the five hundred US companies in the S&P 500 index, if not for seven of them (or eight, if Netflix is included) the index would be down for the year.
These seven or eight companies are all mega-capitalization technology companies: Nvidia (whose chips are currently fueling white-hot artificial intelligence), Apple, Microsoft, Amazon, Meta (formerly Facebook), Alphabet (parent of Google), Tesla, and the 8th is Netflix (arguably as large and hot as the rest).