BD said TRC Capital Investment had made an unsolicited offer to BD shareholders to buy up to 500,000 shares of BD's stock at a price below the current market value.
Nasdaq told the company that its shares have failed to meet a minimum $1 per share closing price for 30 consecutive days and may face delisting action.
Other big gainers last month included Accelerate Diagnostics and Natera, and share prices of 23 of the 27 companies in the index increased month over month.