At least eight firms slashed their price targets for Alphabet, while at least four did the same for Microsoft's stock. Both companies reported earnings per share and revenues below consensus forecasts Thursday.
RBC Capital Markets analysts lowered their price target on Microsoft to $61 from $63 and lowered fiscal fourth-quarter earnings per share and revenue expectations to 56 cents and $22.1 billion from 64 cents and $22.7 billion.
RBC said in a that weaker on-the spot sales of Microsoft's server products and its Office line, as well as a shift in the way it recognizes revenue on those products, led to them lowering their expectations.
Microsoft fell more than 7 percent to close at $51.78.
As for Alphabet, analysts at R.W. Baird said in a Friday note "non-operating losses related to Alphabet's investment portfolio/FX hedges ... were primary drivers of an EPS miss." The analysts cut their Alphabet price target to $860 from $880, but maintained their "outperform" rating on the stock.
Alphabet shares were down 5.4 percent at $737.77.
Combined, the two companies wiped out a total of $53 billion in market cap.
— CNBC's Everett Rosenfeld and Michael Bloom contributed to this report.