Both analysts went from hold to buy although the stock has done "absolutely nothing" of late, TheStreet's Jim Cramer, co-manager of the Action Alerts PLUS portfolio, said on CNBC's "Mad Dash" segment.
The upgrades have given shares a boost above $36, he said, pointing out AT&T's chart has been looking more bullish over the past few sessions.
The analysts at Barclays are optimistic about AT&T's recent acquisition of DirecTV (DTV), while Cramer pointed out the company's dividend coverage is improving.
Turning to Ambarella (AMBA), Cramer said the stock has become a battleground between bulls and bears. While shares have soared on the year, up over 100%, Citron Research's latest bearish note has added plenty of volatility.
Shares are currently up over 8% but before then shares had plunged more than 20% in less than a week.
It's important for investors to remember that Ambarella is more than just a supplier to GoPro (GPRO), Cramer said. It has exposure to drones and security cameras, while also doing business with Comcast (CMCSA) and Chinese smartphone maker Xiaomi.
The "battle is on" between bulls and bears, he said, noting the stock has a 25% short interest.