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) - Get Report, 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) - Get Report, Cramer said. It has exposure to drones and security cameras, while also doing business with Comcast (CMCSA) - Get Report and Chinese smartphone maker Xiaomi.
The "battle is on" between bulls and bears, he said, noting the stock has a 25% short interest.
At the time of publication, Cramer's Action Alerts PLUS had no position in companies mentioned.