** Chip testing equipment maker Teradyne's TER.O shares rise 2.5% to $184.11 in premarket trading
** Stifel upgrades rating to "buy" from "hold," raises PT to $225 from $162
** New PT represents an upside of 25.2% to stock's last closing price
** Average rating of 18 analysts is "buy," their median PT is $197.50 - data compiled by LSEG
** Up to the last close, TER has risen 42.7% this year
(Reporting by Anhata Rooprai in Bengaluru)
((Anhata.Rooprai@thomsonreuters.com))