Elliott Management has sent a letter to Healthcare Trust of America arguing a sale at a “substantial premium” would be a better outcome for shareholders than the company’s current strategy.

Elliott said on Monday that while Healthcare Trust has a “high-quality portfolio” of medical office buildings, increasing competition in the real estate sector is likely to weigh on the company’s market valuation going forward. Elliott added that diversified healthcare REITs and other rivals had a cost-of-capital advantage over Healthcare Trust that made it hard for the company to grow via purchases.

The activist, which says it is one of Healthcare Trust’s largest investors, argued that the REIT is at a “critical juncture” after the abrupt departure of co-founder and CEO Scott Peters and should launch a strategic review to determine the best path ahead.

Peters left the company in early August, a move that gave rise to sale speculation and lifted the stock. Elliott said it believes “highly credible buyers are interested” in acquiring Healthcare Trust “at a meaningful premium to the current trading price.” The activist added that a survey on roughly half of the company’s investor base suggests such a deal would be welcomed by shareholders.

“We believe HTA [Healthcare Trust] will likely be best served by a sale to private equity, a non-traded REIT, or a strategic buyer,” Elliott partner David Miller and portfolio manager Austin Camporin wrote in the letter Monday. “A robust public marketing process, pursued with urgency, would allow the board to take advantage of a favorable market environment and evaluate bids from the full universe of potential buyers,” they added.

In a Monday reaction to Elliott’s letter, Healthcare Trust said it its leadership was aware of the activist’s views due to prior engagement. The REIT added that it was “open minded” about ways to delivering “superior returns” for shareholders.

Healthcare Trust’s stock closed up 2.5% at $32.52 Monday. The shares have risen 18% so far this year but the majority of the gains took place after the departure of CEO Peters. Over a longer five-year period, the stock is up just 3.3%.

Touching on shareholder returns, Elliott noted that Healthcare Trust has underperformed its self-defined closest healthcare REIT peers, broader REIT indices, and the Russell 3000 Index over almost any period in the last five years. This has led to “understandable shareholder frustration and an increasingly impatient investor base, clamoring to see evidence of leadership’s willingness to explore all value-maximizing alternatives,” Elliott argued in the Monday letter, which was posted on a dedicated website.