"has been monopolized" is a correct and usable phrase in written English.
You would use it when speaking or writing about a situation in which one entity has taken exclusive control over something. For example: "The market for luxury cars has been monopolized by the major automakers."
But for generations, political power in Saudi Arabia has been monopolized by an extended royal family.
For nearly two decades, the Winter Garden, where "West Side Story" jump-started his career, has been monopolized by "Cats".
Osteoporosis therapeutics has been monopolized mainly by bisphosphonates, which are potent anti-osteoporotic drugs, while they do not promote bone formation or replenish the already resorbed bone.
LNG tanks are complex in design and building process and high in costs, so LNG tank technology is one of the most advanced ones in the field of energy, which has been monopolized by foreign companies for a long time.
Her cars are relegated to the driveway because her garage has been monopolized by her charity, the Riders Closet; she collects used riding clothing and personally ships it to needy riders, riding groups and collegiate teams.
For more than a decade government has been monopolized by a cozy coalition of Social Democrats and Christian Democrats, a coalition based more on pork barrels and jobs for the boys than ideological compatibility.
By age 4 or 5 they learn the ruse of seeming to be in distress as a way of stealing the microphone from whoever has been monopolizing it.
Lane was speaking now as someone does who has been monopolizing conversation for a good quarter of an hour or so and who believes he has just hit a stride where his voice can do absolutely no wrong.
"RewardStyle has been monopolizing the U.S. and UK, but there's nothing like this in Asia," she explained.
By 1888 the thousands of claims of the previous decade had been monopolized by the De Beers Mining Company.
