Back in January, we revealed that in lieu of QE, which is still on hiatus, the biggest buyer of stocks in 2015 will be corporations themselves, who at the start of the year Goldman estimated were poised to repurchase some $450 billion of their own shares (as "households" were on route to sell a near record $250 billion). Subsequently, we reported that the reason for the relentless surge in the stock market in February following the ghastly January was none other than buybacks alone. In fact, run-rating the February buyback number which was just shy of $100 billion, one can easily state that the previous estimate of $450 billion in total 2015 buybacks will be woefully low. Sure enough, based on a revised estimate by Goldman, the vampire squid now expects companies to repuchase a record $604 billion in 2015, approaching the amount of total liquidity injection during the peak of the Fed's QE. The reason we bring this up is while it is clear to everyone by now that only stock buybacks remain as a bid for stocks (and as we further reported, tech company insiders are now selling record amounts of their personal shares to their own companies!), is that as Goldman revealed overnight, we are now entering a very dangerous period for stocks: the so-called buyback blackout period. So, for those curious what the biggest threat to the S&P's making new daily all time highs is, here is the explanation: The majority of companies just entered the buyback blackout period leading into the 1Q earnings season, and high valuations in the absence of corporate demand may weigh on stock prices. Buybacks remain a major source of demand for equity. We expect S&P 500 firms will boost repurchases by 18% to $604 billion in 2015. While roughly 70% of share repurchases are implemented via 10b5-1 programs, firms refrain from discretionary buybacks during the blackout periods that extend from roughly five weeks prior to earnings reports through 24-48 hours post-announcement. As volumes decline, market performance appears more vulnerable to the seasonality of buyback activity. The closing of the buyback window ahead of earnings season has recently coincided with weaker S&P 500 performance. In half of the last eight quarters, the S&P 500 declined during the four weeks prior to earnings season. The S&P 500 rose an average of 0.3% in the month leading up to earnings season versus +1.6% both during earnings season and in the month following earnings season. How long is the weakness expected to persist? At least until the first week of May when the buybacks resume So be very careful with those S&P 500 sell stops: they just may get triggered in the next 6 weeks. As for will Goldman be doing? Why selling of course. How do we know this? Because it is telling the muppets to buy all it has to sell: Investors should view any market pressure as a buying opportunity. High valuations in the absence of corporate demand may weigh on stock prices. However, we expect the market will climb to 2150 around mid-year 2015 ahead of the anticipated September Fed tightening and as corporate buyback activity resumes once earnings season ends. The closure of the buyback window may lead to a more attractive entry point for investors interested in this strategy. Both GSTHCASH and GSTHREPO are more likely to outperform the market in the month following earnings. Seasonally, the hit rate of outperformance is highest in February, May, and August. We believe stocks with high total cash returns will outperform as S&P 500 firms grow buybacks and dividends by 18% and 7%, respectively, in 2015. In particular, we recommend investors buy our basket of US stocks focused on returning cash to shareholders via buybacks and dividends. And don't worry: Goldman will have more than enough to sell to you, guaranteed.