S&P just downgraded Greece's credit rating to CCC- from CCC. That's about as deep into junk territory as it gets in sovereign credit ratings. The country is a day away from a major debt payment that it cannot pay. Meanwhile, panicked Greeks trying to drain ATMs of whatever cash they can get are being limited by new capital controls. Greek Banks are closed and expected to remain closed through July 5, when Greek Prime Minister Alexis Tsipras has called for a referendum to vote on the latest terms of a bailout agreement set forth by Greece's creditors. "We interpret Greece's decision to hold a referendum on official creditors' loan proposals as a further indication that the Tsipras government will prioritize domestic politics over financial and economic stability, commercial debt payments, and eurozone membership," S&P said. "In our view, the probability of Greece exiting the eurozone is now about 50%," they continued. "Also, we believe that, absent unanticipated favorable changes in Greece's circumstances, a commercial default is inevitable within the next six months." S&P's outlook is officially "negative," which means Greece could be downgraded to SD, or selective default, within six months. Just three weeks ago, the credit rating agency cut the country's rating to CCC from CCC+ while warning its outlook was negative. Here's the statement from S&P: Greece Long-Term Ratings Lowered To 'CCC-'; Outlook Negative RATING ACTIONOn June 29, 2015, Standard & Poor's Ratings Services lowered its foreign and local currency long-term sovereign credit ratings on Greece (Hellenic Republic) to 'CCC-' from 'CCC'. The 'C' short-term ratings were affirmed. The outlook is negative. As defined in EU CRA Regulation 1060/2009 (EU CRA Regulation), the ratings on Greece are subject to certain publication restrictions set out in Art 8a of the EU CRA Regulation, including publication in accordance with a pre-established calendar (see "Calendar Of 2015 EMEA Sovereign, Regional, And Local Government Rating Publication Dates: First-Quarter Update," April 8, 2015, on RatingsDirect). Under the EU CRA Regulation, deviations from the announced calendar are allowed only in limited circumstances and must be accompanied by a detailed explanation of the reasons for the deviation. In Greece's case, the deviation was prompted by the central government's decision to reject official creditors' loan proposals and instead schedule a national referendum on whether to accept the terms of the proposals. The deviation also reflects further deterioration since June 10 of liquidity conditions in Greece's banking system, which depends heavily on official financing from the Eurosystem, the eurozone's monetary authority. This led to the imposition of emergency capital controls in Greece as of yesterday. RATIONALEThe downgrade reflects our assessment that, in the absence of unanticipated favorable changes in circumstances, Greece will likely default on its commercial debt during the next six months. In our view, the Greek government's decision to hold a national referendum on official creditors' loan proposals indicates that Prime Minister Alexis Tsipras will prioritize domestic politics over the country's financial and economic stability, commercial debt service, and membership of the eurozone. We interpret the government's inability to agree with official creditors on a loan program as a sign that it will likely miss payment obligations due on June 30, including the €1.5 billion owed to the International Monetary Fund (IMF). Given that the government appears willing to accept the consequences on its banking sector and economy from the failure to reach an agreement, we now see a 50% likelihood of Greece eventually exiting the eurozone. Should this occur, Greece would permanently lose access to financing from the European Central Bank (ECB), which, in our opinion, would create a serious foreign currency shortage for the private and public sectors, potentially leading to the rationing of key imports such as fuel. Under our methodology, exit from the eurozone would lead us to revise our transfer and convertibility assessment on Greece to 'CCC' from 'AAA' to reflect the loss of a reserve currency and the foreign currency shortage this would create. At present, the Eurosystem's support to Greek banks--directly through the ECB's main refinancing operations and indirectly via the Bank of Greece's Emergency Liquidity Assistance (ELA)--exceeds 70% of GDP, according to our estimates. Without it, Greece's payment system would shut down and its banks would not be able to operate. Despite further deposit withdrawals from Greek banks over the weekend, the ECB has decided not to increase the ceiling on the ELA to Greek banks from the €89 billion agreed on June 26. The Greek Financial Stability Council has declared a bank holiday from June 29 until July 7, 2015. It has also introduced deposit withdrawal limits and controls on transfers abroad. An extended bank holiday involving capital controls will, in our view, further weigh on Greece's economy, which we expect will contract by 3% this year, although the margin of error on this figure is substantial. While failure to make tomorrow's IMF payment would not constitute a commercial default as defined by our criteria, it is a legal event of default under the December 2012 Master Financial Assistance Facility Agreement between Greece and the European Financial Stability Facility (EFSF). Our base-case expectation remains that, over the next several months, the EFSF is unlikely to demand accelerated payment on the €130.9 billion (equivalent to 75.1% of GDP) that it lent Greece. We would not lower our long-term ratings on Greece to 'SD' should the government miss payments on bonds held by the ECB totaling €6.7 billion due in July and August. This is because our sovereign ratings pertain to the central government's ability and willingness to service financial obligations to commercial (that is, nonofficial) creditors (see paragraph 4 of "Sovereign Rating Methodology," published on Dec. 23, 2014), and we consider the ECB to be an official creditor (see also "Greece's Nonpayment of Bonds Held by ECB Would Not Constitute a Default Under Our Criteria," published June 15, 2015). Greece's upcoming commercial debt payments include €2.0 billion in treasury bills due on July 10; €83 million on a Japanese yen obligation, due on July 14; and €71 million in interest, due on July 17 on a three-year commercial bond the government issued in July 2014. About €39 billion of Greece's total medium- and long-term debt is commercial, representing 22% of GDP. All of the remaining €261 billion in debt (excluding €15 billion in treasury bills) is owed to official creditors. OUTLOOKThe negative outlook indicates that we could lower the long-term ratings to 'SD' within the next six months in the event of a distressed exchange or nonpayment of Greece's commercial debt, including treasury bills. We could revise the outlook to stable if we believe that a new financial support program will be agreed, with policy conditions that satisfy both Greece and its official creditors.Join the conversation about this story » NOW WATCH: 6 scientifically proven features men find attractive in women