Offshore companies with strong balance sheets, underpinned by persistently low interest rates, are expected to be running the rule over promising companies which could bolt on to their own operations - such as the Nuplex deal.
Both companies would be delisted, and absorbed into the separate multi-billion dollar US private equity fund companies Insight Venture Partners and Advent International.
Belgian-based resin manufacturer Allnex (owned by Advent) is offering $5.55 per share, at a 41% premium, to buy Nuplex for $1.04billion, while US-based private equity company Insight Venture Partners is offering $7.39, at a 31% premium, to buy Diligent for $NZ941million.
Diligent's shares leapt more than 25% to $7.08 and Nuplex spiked more than 30%, to $5.05.
While Diligent has "entered into a definitive agreement'' to be purchased, the Nuplex sale is an "indicative, non-binding and conditional proposal'', but otherwise is in "advanced discussions'' and due diligence with the aim of reaching a binding agreement.
Nuplex has given Allnex six weeks of "exclusivity'' for the agreement to be pulled together, and will then seek shareholder approval.
Craigs Investment Partners broker Peter McIntyre said while the purchasers were "at first glance'' offering attractive premiums, the companies would appear to be "cheap by US standards''.
"Diligent's sale is not a surprise. It has a lot of its business based in the US,'' he said.
Diligent, which is a provider of secure online services for boards, committees and leadership teams, has revenues of almost $US100million ($NZ150.6million), and 3500 customers worldwide in 60 countries.
Mr McIntyre said the premium for Diligent did not offer a sufficient premium for taking control, customarily 20%-30%, or share enough synergies sufficiently.
However, the takeover looked likely to succeed, given Diligent was incorporated in Delaware, so is subject to takeover rules in that state, requiring only a simple majority of shareholders, of 50%+1, for a takeover to succeed, as opposed to 90% required under NZX rules.
About 50% of Diligent's register was US-based and 50% New Zealand-based, Mr McIntyre said.
Last month, Craigs predicted 2016 would be a year of M&A in the New Zealand market, given the availability of cheap funding, low interest rates and general outlook for New Zealand's economy.
"It's not the last you will see of M&A activity,'' Mr McIntyre said.
Diligent's purchaser, Insight Venture Partners, is a private equity company that was formed in 1995, and has since raised more than $US13billion in capital and invested in more than 250 companies.
Diligent's chairman David Liptak said the board was backing the takeover, as being "in the best interest of stockholders''.
Once filings of proxy materials had been made to the US Securities and Exchange Commission and New Zealand stock exchange, a date for a special meeting of shareholders would be announced.
The Nuplex deal is a little less straightforward.
The Nuplex board had initially rejected the advances of Allnex, which is owned by private equity company Advent International, but after three offer revisions getting to $5.55 per share, Nuplex agreed to further talks and going public on the offer.
Since 1984, Advent has raised about $US40billion in capital, completing more than 310 transactions including more than 30 investments in the chemical-related industry.
A statement from Nuplex said: "The board of Nuplex considers the offer to be attractive for Nuplex' shareholders''.
