Lots of shares have been trading. If this is like every other stock I've owned which has been taken over, longs are selling their shares and arbitrageurs are buying. With 0.5% profit in say 6 months, this bet on a completed takeover is far more lucrative than a bond, especially considering they'll be using leverage. And every arb will vote for completion of the deal, not PWER staying independent.
So would a lawsuit stop the deal? I'd call lawsuits based on forward-looking statements in a conference call 18 months ago a pipe dream, except that would be too charitable.
The only way the ABB deal doesn't happen is if another bidder emerges. Sure ABB gets a $20M breakup fee if PWER takes another offer, but than is less than $0.13/share, an additional 2% to another offer. Any bidder who thinks PWER is worth far more than $6.35 won't balk at another $0.13. IMHO a $20M breakup fee is practically an INVITATION for other bidders to consider a deal. Sure Silverlake is committed to voting their stake for ABB, but every other owner who wants a deal would vote for a higher offer, and selection of the higher offer would only take a majority of shares. IMHO Silverlake's commitment is not a significant hindrance to a higher price.
So how likely is a higher offer? Over the years I've owned 14 stocks when they've been taken over, and only once was there a higher bid. Most of the 14 were smaller market caps and less strategic than PWER so that might make PWER more likely to attract another bid. Then again, the future for solar power is less certain than for the typical industry, and how many CEOs wants to risk his high-paying job by sticking out his neck in a gamble? I'd still say the odds of another bidder are only about 15%. Of course, that is enough to keep me in PWER until I see something else I'd rather do with my money.