"Precision is difficult in a volatile market with daily price swings of +/-5% and a VIX level of 75," the firm wrote in a far-reaching note.
The billionaire, who has some 48,900 Twitter followers but rarely tweets, took to President Donald Trump's preferred communication platform.
Gundlach unwound his short positions amid financial-market carnage and is now reviewing the chance to buy investment-grade art at slashed prices.
If Loeffler—who is married to New York Stock Exchange chairman Jeffrey Sprecher—had held onto those stocks, she would have lost up to $1.5 million.